Power-Constrained Fuzzy Logic Control of Video Streaming over a Wireless Interconnect

Wireless communication of video, with Bluetooth as an example, represents a compromise between channel conditions, display and decode deadlines, and energy constraints. This paper proposes fuzzy logic control (FLC) of automatic repeat request (ARQ) as a way of reconciling these factors, with a 40% saving in power in the worst channel conditions from economizing on transmissions when channel errors occur. Whatever the channel conditions are, FLC is shown to outperform the default Bluetooth scheme and an alternative Bluetooth-adaptive ARQ scheme in terms of reduced packet loss and delay, as well as improved video quality

Evaluation of cross-layer reliability mechanisms for satellite digital multimedia broadcast

This paper presents a study of some reliability mechanisms which may be put at work in the context of Satellite Digital Multimedia Broadcasting (SDMB) to mobile devices such as handheld phones. These mechanisms include error correcting codes, interleaving at the physical layer, erasure codes at intermediate layers and error concealment on the video decoder. The evaluation is made on a realistic satellite channel and takes into account practical constraints such as the maximum zapping time and the user mobility at several speeds. The evaluation is done by simulating different scenarii with complete protocol stacks. The simulations indicate that, under the assumptions taken here, the scenario using highly compressed video protected by erasure codes at intermediate layers seems to be the best solution on this kind of channel

Enhancement of Adaptive Forward Error Correction Mechanism for Video Transmission Over Wireless Local Area Network

Video transmission over the wireless network faces many challenges. The most critical challenge is related to packet loss. To overcome the problem of packet loss, Forward Error Correction is used by adding extra packets known as redundant packet or parity packet. Currently, FEC mechanisms have been adopted together with Automatic Repeat reQuest (ARQ) mechanism to overcome packet losses and avoid network congestion in various wireless network conditions. The number of FEC packets need to be generated effectively because wireless network usually has varying network conditions. In the current Adaptive FEC mechanism, the FEC packets are decided by the average queue length and average packet retransmission times. The Adaptive FEC mechanisms have been proposed to suit the network condition by generating FEC packets adaptively in the wireless network. However, the current Adaptive FEC mechanism has some major drawbacks such as the reduction of recovery performance which injects too many excessive FEC packets into the network. This is not flexible enough to adapt with varying wireless network condition. Therefore, the enhancement of Adaptive FEC mechanism (AFEC) known as Enhanced Adaptive FEC (EnAFEC) has been proposed. The aim is to improve recovery performance on the current Adaptive FEC mechanism by injecting FEC packets dynamically based on varying wireless network conditions. The EnAFEC mechanism is implemented in the simulation environment using Network Simulator 2 (NS-2). Performance evaluations are also carried out. The EnAFEC was tested with the random uniform error model. The results from experiments and performance analyses showed that EnAFEC mechanism outperformed the other Adaptive FEC mechanism in terms of recovery efficiency. Based on the findings, the optimal amount of FEC generated by EnAFEC mechanism can recover high packet loss and produce good video quality

Quality aspects of Internet telephony

Internet telephony has had a tremendous impact on how people communicate. Many now maintain contact using some form of Internet telephony. Therefore the motivation for this work has been to address the quality aspects of real-world Internet telephony for both fixed and wireless telecommunication. The focus has been on the quality aspects of voice communication, since poor quality leads often to user dissatisfaction. The scope of the work has been broad in order to address the main factors within IP-based voice communication. The first four chapters of this dissertation constitute the background material. The first chapter outlines where Internet telephony is deployed today. It also motivates the topics and techniques used in this research. The second chapter provides the background on Internet telephony including signalling, speech coding and voice Internetworking. The third chapter focuses solely on quality measures for packetised voice systems and finally the fourth chapter is devoted to the history of voice research. The appendix of this dissertation constitutes the research contributions. It includes an examination of the access network, focusing on how calls are multiplexed in wired and wireless systems. Subsequently in the wireless case, we consider how to handover calls from 802.11 networks to the cellular infrastructure. We then consider the Internet backbone where most of our work is devoted to measurements specifically for Internet telephony. The applications of these measurements have been estimating telephony arrival processes, measuring call quality, and quantifying the trend in Internet telephony quality over several years. We also consider the end systems, since they are responsible for reconstructing a voice stream given loss and delay constraints. Finally we estimate voice quality using the ITU proposal PESQ and the packet loss process. The main contribution of this work is a systematic examination of Internet telephony. We describe several methods to enable adaptable solutions for maintaining consistent voice quality. We have also found that relatively small technical changes can lead to substantial user quality improvements. A second contribution of this work is a suite of software tools designed to ascertain voice quality in IP networks. Some of these tools are in use within commercial systems today

A low-energy rate-adaptive bit-interleaved passive optical network

Energy consumption of customer premises equipment (CPE) has become a serious issue in the new generations of time-division multiplexing passive optical networks, which operate at 10 Gb/s or higher. It is becoming a major factor in global network energy consumption, and it poses problems during emergencies when CPE is battery-operated. In this paper, a low-energy passive optical network (PON) that uses a novel bit-interleaving downstream protocol is proposed. The details about the network architecture, protocol, and the key enabling implementation aspects, including dynamic traffic interleaving, rate-adaptive descrambling of decimated traffic, and the design and implementation of a downsampling clock and data recovery circuit, are described. The proposed concept is shown to reduce the energy consumption for protocol processing by a factor of 30. A detailed analysis of the energy consumption in the CPE shows that the interleaving protocol reduces the total energy consumption of the CPE significantly in comparison to the standard 10 Gb/s PON CPE. Experimental results obtained from measurements on the implemented CPE prototype confirm that the CPE consumes significantly less energy than the standard 10 Gb/s PON CPE

Implementation and validation of an adaptive FEC machanism for video transmission

This research focuses on investigating the FEC mechanism as an error recovery over a wireless network.The existing adaptive FEC mechanism faces a major drawback, which is the reduction of recovery performance by injecting too many excessive FEC packets into the network. Thus, this paper proposes the implementation of an enhanced adaptive FEC (EnAFEC) mechanism for video transmission together with its validation process.There are two propositions in the EnAFEC enhancement, which include block length adaptation and implementation, and suitable smoothing factor value determination.The EnAFEC adjusts the FEC packets based on the wireless network condition so that excessive FEC packets can be reduced.The proposed enhancement is implemented in a simulation environment using the NS-2 network simulation.The simulation results show that EnAFEC generates less FEC packets than the other types of adaptive FEC (EAFEC and Mend FEC).In addition, a validation phase is also conducted to verify that the proposed enhancement is functioning correctly, and represents a real network situation.In the validation phase, the results obtained from the simulation are compared to the outputs of the other adaptive FEC mechanisms.The validation results show that the mechanism is successfully implemented in NS2 since the number of packet loss falls under the overlapping confidence intervals

Network-aware Adaptation with Real-Time Channel Statistics for Wireless LAN Multimedia Transmissions in the Digital Home

This paper suggests the use of intelligent network-aware processing agents in wireless local area network drivers to generate metrics for bandwidth estimation based on real-time channel statistics to enable wireless multimedia application adaptation. Various configurations in the wireless digital home are studied and the experimental results with performance variations are presented.Comment: 6 pages, 12 figure

A PERFORMANCE STUDY OF ADAPTIVE FEC MECHANISM FOR VIDEO TRANSMISSION OVER 802.11 WLANS

Forward Error Correction has been implemented with Automatic Repeat reQuest to overcome packet losses and avoid network congestion in various wireless network conditions. The number of FEC packets is needed to be generated adaptively due to various network states and burst error condition. There are a number of proposed Adaptive FEC mechanisms that can generate FEC packets adaptively for wireless network. However, this current Adaptive FEC, namely Mend FEC mechanism has major drawbacks including injecting excessive number of FEC packets into the network and consequently reducing recovery performance. This paper proposed an enhancement on Mend FEC mechanism, which is called Enhanced Adaptive FEC (EnAFEC) mechanism. The enhancement is aimed to improve recovery performance of the Mend FEC mechanism by generating FEC packets dynamically based on varying wireless network conditions. The proposed enhancement was implemented in simulation environment using the NS2 network simulation. The results show that EnAFEC mechanism outperformed the other Adaptive FEC mechanism in terms of recovery efficiency. This paper also highlights that even minimal amount of FEC packets can recover high packet losses and achieve good video quality at the receiver

Network Coding-Assisted Retransmission Scheme for Video- Streaming Services over Wireless Access Networks

Video-streaming services, such as Internet protocol television, promising the delivery of multimedia contents over wireless access networks to clients whenever and wherever, are becoming more and more popular. However, scarce radio resources, lossy characteristics of wireless links and high bandwidth demands pose the never-ending challenges for provisioning of real-time streaming services over wireless networks in a timely and reliable manner. Furthermore, a wireless channel may suffer from interference and multipath fading, which may cause random packet losses. In addition, wireless link layer does not provide a retransmission mechanism for multicast/broadcast traffic. This would significantly impact the clients’ quality of experience of streaming services. Traditional unicast retransmission solutions improve client’s quality, at the bandwidth expense, because every lost packet must be retransmitted separately. This chapter presents and practically evaluates a retransmission scheme for video-streaming services over last mile wireless networks. It is based on network coding techniques that increase the overall performance by means of reducing the number of physical transmissions, in comparison to traditional unicast retransmission approach, resulting in reduced bandwidth consumption. Thus, the Internet service providers can increase the number of clients over the same infrastructure or, alternatively, offer more services to the clients