Ala' F. Khalifeh

Efficient PFD-Based Networking and Buffering Models for Improving Video Quality over Congested Links

Video traffic over the Internet becomes increasingly popular and is expected to comprise the largest proportion of the traffic carried by wired and wireless networks. On the other hand, videos are usually compressed by exploiting spatial and temporal redundancy for the reason of increasing the number of video streams that can be simultaneously carried over links. Unfortunately, receiving high-quality video streaming over the Internet remains a challenge due to the packet loss encountered in the congested wired and wireless links. In addition, the problem is more apparent in wireless links due to not only employing limited system capacity, but also some of the major drawbacks of wireless networks, out of which the bandwidth limitations and link asymmetry which refers to the situation where the forward and reverse paths of a transmission have different channel capacities. Therefore, the wireless hops may be congested which result in dropping many video frames. Additionally, as a result of compressing videos, dependencies among frames and within a frame arise. Consequently, the overall video quality tends to be degraded dramatically. The main challenge is to support the growth of video traffic while keeping the perceived quality of the delivered videos high. In this paper, we extend our previous work concerning improving video traffic over wireless networks through professionally studying the dependencies between video frames and their implications on the overall network performance. In other words, we propose very efficient network and buffer models proportionately to novel algorithms that aim to minimize the cost of aforementioned possible losses by selectively discarding frames based on their contribution to picture quality, namely, partial and selective partial frame discarding policies considering the dependencies between video frames. The performance metrics that are employed to evaluate the performance of the proposed algorithms include the rate of non-decodable frames, peak signal-to-noise ratio, frameput, average buffer occupancy, average packet delay, as well as jitter. Our results are so promising and show significant improvements in the perceived video quality over what is relevant in the current literature. We do not end up to this extent, but rather the effect of producing different bit-stream rates by the FFMPEG codecs on aforementioned performance metrics has been extensively studied.

New video discarding policies for improving UDP performance over wired/wireless networks

Summary Multimedia communication over wired and wireless networks becomes a compulsory need for many recent applications. To effectively react to the tremendous demand of video streaming over the Internet, videos are usually compressed by utilizing spatial and temporal redundancy. It is noteworthy to mention that compressing videos may degrade their quality if it is not investigated properly. In other words, as a consequence of exploiting redundancies, frame dependencies emanate, which make discarding frames, because of occupying the whole capacity of network elements, have severe implications on the video quality. Furthermore, transmitting videos over capacity-limited links owing to error-prone channels, power constraints and bandwidth variations will severely affect the video quality. Additionally, as the current coding schemes are characterized by being able to afford high compression efficiency, sensitivity to packet losses becomes untolerated. Therefore, insuring the perceived quality of the delivered videos to be always high in spite of aforementioned challenges is the primary focus of current researchers. In this paper, we propose efficient and novel video discarding policies that mainly aim to reduce the number of frames being lost through substitution of those frames that are very difficult or even impossible to decode at the receiver side. This is accomplished by controlling and maintaining the buffer occupancy of network elements. Our proposed policies are evaluated in terms of frameput, rate of non-decodable frames, peak signal-to-noise ratio, structural similarity index and average buffer occupancy. Our proposed policies behave very well and achieve a remarkable enhancement over what is closely connected in the literature. Copyright

Mobile-free driving with Android phones: System design and performance evaluation

Texting while driving is becoming a major problem in many countries worldwide, which if not handled properly can cause serious accidents. In this paper, we present our proposed system for a voiced based text messaging system utilizing Android phones empowered by Google voice recognition engine. We also present some of the software engineering challenges encountered during implementation. Utilizing our software, the user can issue voice commands to his mobile phone which in turn will send the text message on his behalf. Furthermore, we tested the performance of our system with different people that have different English accents, and under different background noise. Our performance analysis showed that there is a need to develop and enhance the current Google API voice recognition engine to better support people with different English accents. Moreover, the current APIs should allow the developer to add some signal processing functionalities to eliminate the effect of the background noise that the user may encounter while driving.

Intelligent and Selective Video Frames Discarding Policies for Improving Video Quality over Wired/Wireless Networks

Although IEEE 802.11 Wireless LAN (WLAN) is of a great interest nowadays, it lacks the efficient capability of supporting real-time streaming which is due to mainly the contention nature of wireless media. In this paper, we extend our earlier work concerning improving video traffic over wireless networks through effectively studying the dependencies between video frames and their implications on the overall network performance. In other words, we propose very efficient and novel algorithms that aim to minimize the cost of possible losses by intelligently and selectively discard frames based on their contribution to picture quality, namely, partial and intelligent-partial frame discarding policies considering the dependencies between video frames. The performance metrics that are employed to evaluate the performance of the proposed algorithms include the rate of non-decodable frames and peak signal-to-noise ratio (PSNR). Our results are promising and show significant improvements in the perceived video quality over what is relevant in the current literature.

Scheduling and allocation of time-triggered and event-triggered services for multi-core processors with networks-on-a-chip

Multi-core processors are gaining increasing importance in safety-relevant embedded real-time systems, where temporal guarantees must be ensured despite the sharing of on-chip resources such as processor cores and networks-on-a-chip. At the same time, many applications comprise workloads with different timing models including time-triggered and even-triggered communication. This paper introduces a scheduling model based on Mixed Integer Linear Programming (MILP) supporting the allocation of computational jobs to processing cores as well as the scheduling of messages and the selection of paths on networks-on-a-chip. The model supports dependencies between computational jobs and it combines both time-triggered and event-triggered messages. Phase-alignment of time-triggered messages is performed, while avoiding collisions between time-triggered messages and satisfying bandwidth constraints for event-triggered messages. Example scenarios are solved optimally using the IBM CPLEX optimizer yielding minimal computational and communication latencies.

Performance evaluation of Voice-Controlled Online Systems

With the increasing importance of Online Systems, in which a voice over Internet Protocol (VoIP) client can remotely interact and send a voice control commands, the reliability of such systems under different network impairments such as packet loss, delay, delay variation (Jitter), and the link bandwidth becomes a challenge. In this paper, the effect of Quality of Service (QoS) parameters of the network on the Voice-Controlled Online Systems is thoroughly investigated, and a set of recommended bounds on these parameters is proposed.

EA-CRP: A Novel Energy-aware Clustering and Routing Protocol in Wireless Sensor Networks

Abstract This paper proposes a novel energy-aware and layering-based clustering and routing protocol (EA-CRP) for gathering data in WSNs. The main goal of EA-CRP is to reduce the energy consumption among all sensor nodes in the network. To achieve this goal, EA-CRP employs an innovative multilayered architecture. More specifically, we divide the field into a number of layers where the width of a layer not only decreases towards the base station, but also is composed of a certain number of clusters (sub layers). The proposed design not only shortens the communication distance between nodes, but also decreases the amount of communication overhead required for setting up clusters. Furthermore, a multi-hop routing algorithm for inter-cluster communications is proposed which basically considers the tradeoff between distance and the energy of relaying nodes. The effectiveness of EA-CRP is verified through comparing its results with those obtained from previous relevant protocols. Interestingly, our experimental results show that EA-CRP has superior performance in term of network lifetime, energy efficiency, and scalability.

A videoconferencing platform for eHealth services in Jordan

With the tremendous Internet proliferation, people started to utilize it in their daily life activities. Electronic health (eHealth) is a promising strategy for delivering health care services over the Internet where patients can interact with their health professionals through videoconference sessions to obtain health advices and follow-up information on their health conditions, and exchange views with their health professionals. In this paper, an e-health videoconferencing platform is described along with its potential usage in the Jordanian healthcare system and, in particular, medical centers and hospitals located in the rural areas. The paper also presented some relevant technical and social challenges.

Experimental testbed for video streaming analysis based on RTMF protocol

Internet-based video communications have been gaining increasing popularity in recent years and thus, the need for improving quality of service has become an essential requirement. This paper presents an experimental testbed that is based on the real-time media flow protocol (RTMFP). The proposed testbed enables experimental investigations of the impact of key video-quality parameters such as the frame quality, frame rate, and resolution on the video quality at various speeds of video streaming, and network conditions. It also allows for developing adaptation algorithms that can be utilized in real-time video transmission to ensure delivery of best service possible under various network conditions. The hardware and software aspects of the testbed are presented along with the practical setup and configuration commands. Some of the practical challenges faced throughout the implementation and test phases are presented. Performance of the developed prototype is assessed experimentally and some of the obtained results are also presented and discussed.

Shadowing effects on visible light communication channels

It is well known that the effect of shadowing on a visible light communication (VLC) system is severe due to its line of sight propagation nature. Hence, shadowing can seriously impair the system performance. In this paper, we propose a method to take advantage of the optical diffraction phenomenon to overcome shadowing by employing a receiver with a wide field-of-view (FOV). We have modelled the shadowing effect for visible light by a Bimodal Gaussian distribution and derived the probability of error for low, moderate and severe shadowing conditions. The Bimodal Gaussian distribution effectively represents separate propagation modes caused by different polarizations. This approach is useful in both indoor and outdoor environments.