Abstract Security vulnerabilities of the modern Internet of Things (IoT) systems are unique, mainly due to the complexity and heterogeneity of the technology and data. The risks born out of these IoT systems cannot easily fit into an existing risk framework. There are many cybersecurity risk assessment approaches and frameworks that are under deployment in many governmental and commercial organizations. Extending these existing frameworks to IoT systems alone will not address the new risks that have arisen in the IoT ecosystem. This study has included a review of existing popular cyber risk assessment methodologies and their suitability to IoT systems. National Institute of Standards and Technology, Operationally Critical Threat, Asset, and Vulnerability Evaluation, Threat Assessment & Remediation Analysis, and International Standards Organization are the four main frameworks critically analyzed in this research study. IoT risks are presented and reviewed in terms of the IoT risk category and impacted industries. IoT systems in financial technology and healthcare are dealt with in detail, given their high-risk exposure. Risk vectors for IoT and the Internet of Medical Things (IoMT) are discussed in this study. A unique risk ranking method to rank and quantify IoT risk is introduced in this study. This ranking method initiates a risk assessment approach exclusively for IoT systems by quantifying IoT risk vectors, leading to effective risk mitigation strategies and techniques. A unique computational approach to calculate the cyber risk for IoT systems with IoT-specific impact factors has been designed and explained in the context of IoMT systems.

Current live eLearning systems enable remote students to view the teaching environment comprising of several information sources such as the teacher and the teaching aids. These information sources are presented as individual video and audio elements. As a result, spatial connections between these elements, such as the teacher using hand gestures to point to an area on the screen, become meaningless at the remote location. Moreover, the remote students are required to divide their attention between multiple visual elements such as the screen displaying presentation slides and a separate screen displaying the teacher. This division in attention results in students getting disengaged from the class. This paper outlines a presentation architecture which preserves the spatio-temporal correlation amongst the multimedia elements. The architecture requires calibration of correlation data, capture of information sources, streaming to remote participating locations and compositing the received streams using feature matching techniques into a unified multilayered video presentation. A real-time virtual teaching environment is created for live eLearning sessions, which closely mimics a natural environment. The outcome is an engaging environment for the remote students. Also, the system does not impose any restrictions on the natural teaching style used by the teacher. A user study was performed comparing the proposed system to the current common existing representation. The results indicate a marked improvement in the classroom experience for the remote students.

E-Learning technologies focus on methods to replicate entities such as white board, presentation screen and other teaching aids in remote classrooms. Often, a high detail video stream of the whiteboard or presentation screen (board-stream) is streamed to the remote classroom along with the instructor’s video stream. However, remote participants find it difficult to correlate between the two displayed streams to find out the area focused by the instructor‘s gestures such as finger pointing over the board. This paper deals with a method to overlay the instructor's contour-extracted frames from the instructor-stream over the board-stream for remote participants. Since the board-stream and instructor-stream have different camera perspectives, a transformation from the instructor’s video perspective to the board-stream perspective has to be made before overlay. The process includes finding the Homography-matrix, warping and overlay. Our performance results indicate that remote participants are able to discern the area focused by the instructor on the board with much greater accuracy and speed.

Time series data from sensor devices are increasingly stored in log data structures across the cloud and mobile devices. Currently, log data is accessed as chunks of fixed size, which enhances performance by prefetching of data. However, in applications such as remote monitoring of patients using mobile devices, data requirement of end users varies significantly depending upon their roles. The fixed chunking approach would lead to unnecessary data download due to the dynamic variability of data access. Also, the requests are more often than not based on fixed time chunks that do not necessarily translate to fixed data size. To overcome this challenge, we present a dynamic log chunking mechanism based on reader access pattern and domain specific data characteristics. The application of this method in the area of remote patient monitoring in bandwidth starved rural areas is shown to result in bandwidth and cost savings of 14% without affecting the prefetch performance.

We present a location detection system for tracking multimedia appliances and users within a wireless local area network (WLAN) enabled home environment. Multimedia appliances communicate with a central gateway via low cost network interface devices called buddies. The gateway can locate the users and appliances within the accuracy of a room and use the location information to automatically redirect media streams to user's presence. We call this paradigm as a media cloud. This paper presents the scheme for collecting proximity information from the buddies and effective techniques to determine their location. We have implemented the location detection system and present an experimental performance evaluation.

Wireless LANs based on the IEEE 802.11 technology are becoming increasingly prevalent. Te availability of high bandwidth together with the convenience of being a wireless medium makes it a compelling technology for multimedia-based applications. In this paper, we present a gateway-based architecture of the wireless home media network and develop a secure registration protocol that is appropriate for such an architecture. The primary goal of the protocol is to provide a secure bootstrap registration mechanism for a new media appliance and to ensure a secure communication path between appliances and the gateway that minimizes the resource usage at the appliance.

This paper presents and analyzes user behavior and network performance in a public-area wireless network using a workload captured at a well-attended ACM conference. The goals of our study are: (1) to extend our understanding of wireless user behavior and wireless network performance; (2) to characterize wireless users in terms of a parameterized model for use with analytic and simulation studies involving wireless LAN traffic; and (3) to apply our workload analysis results to issues in wireless network deployment, such as capacity planning, and potential network optimizations, such as algorithms for load balancing across multiple access points (APs) in a wireless network.

When a group {/1,..., l/sub n/} of individuals wishes to collaboratively construct a complex multimedia document, the first requirement is that they be able to manipulate media-objects created by one another. For instance, if individual L/sub j/ wishes to access some media objects present at participant l/sub k/'s site, he must be able to: 1) retrieve this object from across the network, 2) ensure that the object is in a form that is compatible with the viewing/editing resources he has available at his node, and 3) ensure that the object has the desired quality (such as image size and resolution). Furthermore, he must be able to achieve these goals at the lowest possible cost. In this paper, we develop a theory of media objects, and present optimal algorithms for collaborative object sharing/synthesis of the sort envisaged above. We then extend the algorithms to incorporate quality constraints (such as image size) as well as distribution across multiple nodes. The theoretical model is validated by an experimental implementation that supports the theoretical results.

The requirement of continuous retrieval, and the presence of multiple media streams whose display must proceed in a mutually synchronized manner are the distinguishing features that are unique to digital multimedia. In the emerging international multimedia encoding standard MPEG, continuity and synchronization are handled at different layers of the multimedia stream. The authors discuss how they are specified and propose techniques for their implementation within a distributed multimedia environment.

Future advances in storage and networking technologies will make it feasible to build multimedia on-demand information servers capable of providing services similar to those of a neighborhood videotape rental store over metropolitan area networks. Such multimedia information servers must not only support retrieval of continuous media units (such as video frames and audio samples), but also preserve synchrony among playback of the different media components constituting a multimedia object. We develop techniques for supporting continuous and synchronous retrieval from multimedia servers. We present feedback techniques by which, during retrieval of multimedia objects from a multimedia server to mediaphones, the multimedia server uses lightweight messages called feedback units transmitted periodically back to it (by mediaphones) to detect impending discontinuities as well as asynchronies at mediaphones. The multimedia server then preventively readjusts media transmission so as to avoid either anomaly, and steers the mediaphones back to synchrony. Given the available buffer sizes at mediaphones and the maximum tolerable asynchrony, we present methods to determine the minimum rate at which feedback units must be transmitted so as to maintain both continuity and synchronization. These feedback techniques remain robust even in the presence of playback rate mismatches and network delay jitter, and their initial simulation for video-audio playback yields a feedback rate of one per 1,000 media units to keep the asynchrony within 250ms, showing that the overhead due to feedback transmission is very small. The constant rate feedback techniques developed in this article form the basis of a prototype on-demand information server being developed at the UCSD Multimedia Laboratory.

Future advances in networking and storage will make it feasible to build multimedia on-demand servers that provide services similar to those of a neighbourhood videotape rental store over metropolitan area networks such as B-ISDN. Such multimedia servers can support real-time retrieval of multimedia objects by users onto their ISDN videophones and audiophones for playback. The design of techniques and protocols for providing continuous and synchronous access to multimedia services constitutes the subject matter of this paper. In future integrated networks, mediaphones that possess bare minimum capability to playback media but which lack the sophistication to run elaborate time synchronization protocols, may be connected directly to the network. We present rate-based feedback strategies by which, during retrieval, a multimedia server uses light-weight messages called feedback units transmitted periodically to mediaphones, to accurately estimate the playback instants of media units. Using these estimates, the multimedia server detects impending playback discontinuities due to buffer overruns or starvations at mediaphones, and preventively readjusts media transmission so as to avoid either of these anomalies. Given the available buffer sizes at mediaphones, we present methods by which a multimedia server can determine the minimum rate at which feedback units must be transmitted to it by the mediaphones, so as to maintain continuity of media playback. In order to guarantee synchronous playback at mediaphones, we first propose a bounded buffering technique which uses buffering limitations, at the slave mediaphones to automatically enforce bounds on the asynchrony among mediaphones. Although simple and easy to implement, this technique may entail a large average asynchrony, in order to avoid which we propose a multiple feedback synchronization technique. We present initial performance comparisons of the effectiveness of these synchronization techniques. The techniques for intra-media continuity and inter-media synchronization presented in this paper from the basis of a prototype multimedia on-demand server being developed at the UCSD Multimedia Laboratory.

The authors present a quantitative study of designing a multiuser HDTV server, and they present efficient techniques for storing multiple HDTV videos on disk and servicing multiple subscriber requests simultaneously, both under the constraint of guaranteeing HDTV playback rates. They develop a model that relates disk and device characteristics to the HDTV playback rate and derive a storage pattern for HDTV video streams that guarantees their real-time retrieval. Given multiple HDTV streams, mechanisms for merging their individual storage patterns are developed. Merging algorithms that yield a large improvement in space utilization over storing each of the streams independently are proposed. Policies such as round robin and quality proportional for servicing multiple subscribers simultaneously are studied. These studies provide a quantitative demonstration of the technological feasibility and economic viability of HDTV-on-demand servers on metropolitan area networks (MANs).>

The problem of collocational storage of media strands, which are sequences of continuously recorded audio samples or video frames, on disk to support the integration of storage and transmission of multimedia data with computing is examined. A model that relates disk and device characteristics to the playback rates of media strands and derives storage patterns so as to guarantee continuous retrieval of media strands is presented. To efficiently utilize the disk space, mechanisms for merging storage patterns of multiple media strands by filling the gaps between media blocks of one strand with media blocks of other strands are developed. Both an online algorithm suitable for merging a new media strand into a set of already stored strands and an offline merging algorithm that can be applied a priori to the storage of a set of media strands before any of them have been stored on disk are proposed. As a consequence of merging, storage patterns of media strands may become perturbed slightly. To compensate for this read-ahead and buffering are required so that continuity of retrieval remains satisfied are also presented.>

The authors have developed intermedia synchronization techniques for multimedia on-demand retrieval over integrated networks in the absence of global clocks. In these techniques, multimedia servers use lightweight messages called feedback units transmitted by media display sites (such as audiophones and videophones, generically referred to as mediaphones) to detect asynchronies among those sites. They present strategies by which the multimedia server can adaptively control the feedback transmission rate from that mediaphone, so as to minimize the associated overheads without permitting the asynchrony to exceed tolerable limits. They compare the performance of various resynchronization policies such as conservative, aggressive, and probabilistic. Performance evaluation of the feedback techniques indicates that their overheads are negligible; for a typical audio/video playback environment, the feedback frequency was about one in a hundred.>

The problem of media mixing that arises in teleconferencing applications such as teleorchestra is addressed. The mixing algorithm presented minimizes the difference between generation times of the media packets that are being mixed together in the absence of globally synchronized clocks, but in the presence of jitter in communication delays on packet switched networks. In order to support applications, such as teleorchestra, that involve a large number of participants, hierarchical mixing architectures are proposed, and it is shown that they are an order of magnitude more scalable than purely centralized or distributed architectures. Furthermore, mechanisms for minimizing the delays incurred by mixing in various communication architectures are presented. The mixing algorithms are implemented on a network of workstations connected by Ethernets, and the performance of various mixing architectures is experimentally evaluated. The results reveal the maximum number of participants that can be supported in a conference.>

A secure network protocol called the authenticated datagram protocol (ADP) that optimizes the performance of global networks by establishing host-to-host secure channels and building agent-to-agent channels on top of host-to-host channels is presented. The performance advantages of ADP come with an accompanying set of trust requirements that are stringent for a network spanning mutually distrustful organizations. The cause for this stringency is shown to be propagation of trust relationships in ADP. Methods of breaking their propagation and thereby accomplishing a significant reduction in ADP's trust requirements are presented. ADP, being a protocol for establishing host-to-host channels, can be handled at the subtransport level of the protocol hierarchy. A prototype of ADP implemented on Sun workstations connected by an Ethernet is described. Experimental measurements confirm that both the average latency of messages and the maximum throughput are substantially better than other secure protocols.>

Future advances in networking and storage will enable a wide spectrum of computer mediated structured collaborations among individuals. In this paper, we present a model that can capture diverse types of structured collaborations. The model combines both efficiency and power via a hierarchy of three abstractions, at the lowest level of which are streams for media communication modulated by access rights of participants within collaborations. The higher two levels of abstractions are sessions, which represent collections of semantically related media streams, and conferences, which represent temporally related sequences of sessions. Using these abstractions, the model supports unification of both synchronous and asynchronous collaborations, sophisticated access control, and intra-group and inter-group collaborations, yielding a powerful set of building blocks for constructing multimedia applications and a rich environment for carrying out structured multimedia collaborations. KEYWORDS ...

The design of techniques and protocols for media mixing and communication architectures that optimize the performance of media mixing are discussed. The performance of monostage and multistage techniques for mixing are compared. Centralized and distributed architectures are analyzed for their suitability to both monostage and multistage media mixing, and hierarchical architectures that significantly reduce bandwidth consumption are presented. Algorithms for designing hierarchies that optimize real-time end-to-end delays and a packet train protocol in which the routing nodes can be used as mixers are proposed.>

We address the unique requirements of a multimedia file system such as continuous storage and retrieval of media, maintenance of synchronization between multiple media streams, and efficient manipulation of huge media objects. We present a model that relates disk and device characteristics to the recording rate, and derive storage granularity and scattering parameters that guarantee continuous access. In order for the file system to support multiple concurrent requests, we develop admission control algorithms for determining whether a new request can be accepted without violating the realtime constraints of any of the requests.We define a strand as an immutable sequence of continuously recorded media samples, and then present a multimedia rope abstraction which is a collection of individual media strands tied together by synchronization information. We devise operations for efficient manipulation of multi-stranded ropes, and develop an algorithm for maintaining the scattering parameter during editing so as to guarantee continuous playback of edited ropes.We have implemented a prototype multimedia file system, which serves as a testbed for experimenting with policies and algorithms for multimedia storage. We present our initial experiences with using the file system.

Software mechanisms that make use of analog transmission and storage of video for computer-controlled video communication and file storage are described. The authors extended the Etherphone voice management system to support video conferencing and file storage. The software mechanisms for conference management consist of a central connection manager, and video and user interface agents running on client workstations. A conferencing architecture that supports multiplicity in the number of conferences and media is presented. The video file server stores and retrieves full-motion video information within conferences. It uses optical disks to store video frames and builds a high-level file and directory interface. The user interface to the directory interface is a multimedia document editor that permits video annotations to be freely interspersed with text. The performance of the system, which spans multiple media networks, has been highly satisfactory.>

He introduces basic notions about developing a logic or a theory, and shows that modal logics of belief, with their Kripe-style possible-worlds semantics, are appropriate for basing a theory of trust on. He reviews a modal logic of belief, and constructs a model of the distributed system so that the logic is sound and complete with respect to the model. Any sentences in the logic may then be added to the logic as axioms, and these axiomatic sentences are considered as trust specifications. He presents methods to map a formal trust specification on to mechanisms for its implementation in the distributed system. Trust and security are closely related in distributed systems. It is shown how security specification and verification methods can be integrated into the presented theory of trust. The author analyzes the trusts required in public-key-based secure communication.>

We propose a secure communication architecture for distributed systems that puts security below the transport level, and uses host-to-host rather than process-to-process secure channels. We argue that this provides the same level of end-to-end security as putting security at higher levels, and that it can simplify and improve the performance of transport protocols. The architecture is designed for very large distributed systems, which in general have security requirements beyond those of LAN-based systems.