Multimedia content is massively generated from various applications and devices, and processed in cloud data centers. Multimedia service providers prefer that their data are processed in data centers close to users in order to offer them high performance and reliable multimedia services that meet the requirements specified in the Service Level of Agreement (SLA). This requires transferring huge data sets of video streams, games content, images etc. across geographically distributed cloud data centers using underutilized bandwidth in backbone transport networks. As the amount of multimedia content increases, the demand to transfer big data sets across data centers increases as well. As such, the leftover bandwidth that appears at different times and for different durations in the backbone network becomes insufficient to satisfy the rapidly increasing demand for multimedia big data transfer. This challenge led to the creation of multi-rate Bandwidth on-Demand (BoD) service offerings for communication between geographically distributed cloud data centers. In this paper, we focus on BoD services which are offered by the Dense Wavelength Division Multiplexing (DWDM) layer because of its huge capacity. We propose a BoD broker which employs a scheduling algorithm that considers various deadlines of multimedia big data transfer requests. The broker in our model leverages the concept of standby wavelengths to minimize peak traffic and accommodate time requirements of delay-tolerant and delay-intolerant transfer requests. We also study strategies of routing and wavelength assignment using Mixed Integer Programming (MIP) optimization to rapidly handle volumes of multimedia big data transfer requests.

Conflict is one of the important factors affecting user satisfaction and trust in smart environments, yet conflict modeling in mixed initiative smart environments has not been sufficiently explored. Most of the existing literature on conflict in smart homes are centered on conflicts between users. Although research has shown that about 75% of conflicts are between users and system [1], only a few studies have considered user-system conflicts in smart homes. The aim of this article is to empirically propose both a definition and a run-time detection method for conflicts between users and smart home systems. Our empirical study is based on conflict sample scenarios collected from 163 users. Using clustering on these scenarios, we form an empirical definition of user-system conflict in smart homes. We also propose two functions that characterize each class of the collected scenarios, and we detect conflicts from this characterization. Our conflict detection model could help users achieve a more satisfactory experience in smart homes. Moreover, the model can offer benefits for system developers to design and deploy more reliable smart homes.

An important challenge in smart environments is how to manipulate the smart objects. Although mobile applications are typically used for controlling a smart environment, no previous study has evaluated the users performance in manipulating smart objects under different environmental complexities. This article presents an experimental comparison between three different selection techniques 3-D, 2-D, and physical user interfaces (UIs). We evaluate these techniques across two levels of environment complexity measuring 51 participants timing data and errors. Our results indicate that the 3-D UI is superior for task completion time and error, and the 2-D UI is not a better solution than the physical UI when the environment is not complex. The results also show the importance of considering the environment complexity in choosing the proper UI.

The problem of bounding the reliability function of a multiple access channel (MAC) is studied. Two new upper bounds on the error exponent of a two-user discrete memoryless (DM)-MAC are derived. The first bound (sphere packing) is an upper bound on the exponent of the average probability of error and is the first bound of this type that is zero outside the capacity region and thus results in a tighter sphere-packing exponent when compared with the tightest known exponent derived by Haroutunian. The second bound (minimum distance) is an upper bound on the exponent of the maximal (as opposed to average) probability of error. To obtain this bound, first, an upper bound on the minimum Bhattacharyya distance between codeword pairs is derived. For a certain class of two-user DM-MACs, an upper bound on the exponent of maximal probability of error is derived as a consequence of the upper bound on the minimum Bhattacharyya distance. We analytically evaluate the sphere packing bound for uniform composition codes for an additive and nonsymmetric channel and show that it is tight near the boundary of the capacity region, i.e., equal to the random coding lower bound.

A unified approach is presented for the derivation of reliability function lower bounds for the two-user discrete memoryless (DM) multiple-access channel (MAC). In particular, three lower bounds are presented. The first one (random coding) is identical to the best known lower bound on the reliability function of DM-MACs. It is shown that the random coding bound characterizes the performance of the average code in the constant-type code ensemble. The second bound (typical random coding) characterizes the typical performance (the performance of a high probability subset of the ensemble) of the constant-type code ensemble. To derive the third bound (expurgated), we eliminate some of the codewords from each of the codebooks. This is the first bound of this type that explicitly uses the method of expurgation for DM-MACs. It is shown that the exponent of the typical random coding and the expurgated bounds are greater than or equal to the exponent of the known random coding bounds for all rate pairs. Moreover, an example is given where the exponent of the expurgated bound is strictly larger for a certain input distribution. Each of the presented bounds is universal in the sense that there exists a code that attains the bound for all channels with given input and output alphabets. The approach presented for the DM-MAC is first demonstrated for the point-to-point discrete memoryless channel (DMC), by rederiving the random coding and expurgated exponents, and deriving a bound that characterizes the typical performance of the constant-type code ensemble.

Wide-spread availability of broadband internet access and the ubiquity of thin smart end devices such as smart-phones and tablets have led to a trend of moving more services away from the end devices to data centers, commonly referred to as Cloud Computing. For gaming, the stringent network bandwidth requirements of Cloud Gaming and the rapid growth of massively multiplayer online games (MMOG) call for novel content encoding and scene customization schemes to control the bit rate of the streaming video of the game scene. In this paper, a first step has been taken towards this goal by presenting a selective object encoding method to reduce the required network bandwidth and processing power without much impact on the player's quality of experience.

Throughout various complex processes within hospitals, context-aware services and applications can help to improve the quality of care and reduce costs. For example, sensors and radio frequency identification (RFID) technologies for e-health have been deployed to improve the flow of material, equipment, personal, and patient. Bed tracking, patient monitoring, real-time logistic analysis, and critical equipment tracking are famous applications of real-time location systems (RTLS) in hospitals. In fact, existing case studies show that RTLS can improve service quality and safety, and optimize emergency management and time critical processes. In this paper, we propose a robust system for position and orientation determination of equipment. Our system utilizes passive (RFID) technology mounted on flooring plates and several peripherals for sensor data interpretation. The system is implemented and tested through extensive experiments. The results show that our system's average positioning and orientation measurement outperforms existing systems in terms of accuracy. The details of the system as well as the experimental results are presented in this paper.

In this paper, we describe our proposed mechanism for a context-aware progressive 3D streaming for virtual environments (VEs) such as games running on mobile handheld devices. Our goal is to optimize the efficiency of streaming update messages in such environments by providing a new, dynamic, and context-aware method for selecting and prioritizing objects.

Intelligent Environments have the vision of enhancing our everyday environment and interaction with its objects by sensing, computing, and communication capabilities. The major characteristics of such environments are the increasing number of embedded intelligent devices (ubiquity) into the background (transparency). These devices are expected to disappear or blend into the background and will be invisible to the user. However, because of this transparency, users fail to develop an adequate mental model for interaction with such environments. The Ubiquitous Meta User Interfaces (Ubi-MUI) ACM workshop provides a venue for the development of highly intuitive, multimedia supported meta user interfaces that bring transparency, predictability, and control into intelligent environments.

With the rapid development of applications in open distributed environments such as eCommerce, privacy of information is becoming a critical issue. Information about the preferences, activities, and demographic attributes of people using online shopping is very valuable to online businesses. Beyond the general anxieties with sharing personal information, people may more specifically have concerns about becoming increasingly identifiable; as increasing amounts of personal data are acquired. Not only that, but also it is widely known that information about consumers is often sold to online marketing and advertising companies, generally without the knowledge of consumers [4, 16]. In this paper, we introduce a model where people can opt out to share personal information for a payoff value that balances out the costs of privacy. Our model is based on agents working on behalf of consumers to maximize their benefit. The analysis of the model and a proof of concept implementation are presented in this paper.

Let X and Y be finite alphabets and PXYa joint distribution over them, with PXand PYrepresenting the marginals. For any ϵ > 0, the set of n-length sequences xnand ynthat are jointly typical according to PXYcan be represented on a bipartite graph. We present a formal definition of such a graph, known as a typicality graph, and study some of its properties. These properties arise in the study of several multiuser communication problems.

The problem of bounding the reliability function of a multiple-access channel (MAC) is studied. An upper bound on the minimum Bhattacharyya distance between codeword pairs is derived. For a certain large class of two-user discrete memoryless (DM) MAC, a lower bound on the maximal probability of decoding error is derived as a consequence of the upper bound on Bhattacharyya distance. Further, an upper bound on the average probability of decoding error is studied. It is shown that the corresponding upper and lower bounds have a similar structure. Using a conjecture about the structure of the multi-user code, a tighter lower bound for the maximal probability of decoding error is derived and is shown to be tight at zero rates.

In this paper, we present a metadata-based compressed-domain spatial adaptation scheme for H.264/AVC video. We have enhanced the H.264/AVC encoder with our proposed adaptation strategies in order to reduce video size by cropping individual frames in an intermediary node prior to transmitting that video to heterogeneous devices. In this regard, we exploit the sliced architecture of the video frames within the first version of the H.264/AVC specification and devise different slicing strategies. The compressed-domain bitstream modification is performed at the intermediary nodes, avoiding the need for any cascaded operations. Here, we briefly present our adaptation scheme as well as evaluation results showing the effectiveness of the slicing strategies on the bitrate reduction and processing time. A comparison of our approach with an existing cropping scheme is also presented.

In this work, a new lower bound for the maximal error probability of a two-user discrete memoryless (DM) multiple-access channel (MAC) is derived. This is the first bound of this type that explicitly imposes independence of the userspsila input distributions (conditioned on the time-sharing auxiliary variable) and thus results in a tighter sphere-packing exponent when compared to the tightest known exponent derived by Haroutunian.