Enhanced Wireless Video Transmission Using a Cross-layer Design
Author: Victoria Sgardoni
Publisher:
Published: 2012
Total Pages: 0
ISBN-13:
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Author: Victoria Sgardoni
Publisher:
Published: 2012
Total Pages: 0
ISBN-13:
DOWNLOAD EBOOKAuthor: Rashvand, Habib F.
Publisher: IGI Global
Published: 2012-04-30
Total Pages: 656
ISBN-13: 1466609613
DOWNLOAD EBOOKAlthough the existing layering infrastructure--used globally for designing computers, data networks, and intelligent distributed systems and which connects various local and global communication services--is conceptually correct and pedagogically elegant, it is now well over 30 years old has started create a serious bottleneck. Using Cross-Layer Techniques for Communication Systems: Techniques and Applications explores how cross-layer methods provide ways to escape from the current communications model and overcome the challenges imposed by restrictive boundaries between layers. Written exclusively by well-established researchers, experts, and professional engineers, the book will present basic concepts, address different approaches for solving the cross-layer problem, investigate recent developments in cross-layer problems and solutions, and present the latest applications of the cross-layer in a variety of systems and networks.
Author: Mohamed Ibnkahla
Publisher: CRC Press
Published: 2018-10-08
Total Pages: 428
ISBN-13: 135183570X
DOWNLOAD EBOOKAdaptive techniques play a key role in modern wireless communication systems. The concept of adaptation is emphasized in the Adaptation in Wireless Communications Series through a unified framework across all layers of the wireless protocol stack ranging from the physical layer to the application layer, and from cellular systems to next-generation wireless networks. Adaptation and Cross Layer Design in Wireless Networks is devoted to adaptation in the data link layer, network layer, and application layer. The book presents state-of-the-art adaptation techniques and methodologies, including cross-layer adaptation, joint signal processing, coding and networking, selfishness in mobile ad hoc networks, cooperative and opportunistic protocols, adaptation techniques for multimedia support, self –organizing routing, and tunable security services. It presents several new theoretical paradigms and analytical findings which are supported with various simulation and experimental results. Adaptation in wireless communications is needed in order to achieve high capacity and ubiquitous communications. The current trend in wireless communication systems is to make adaptation dependent upon the state of the relevant parameters in all layers of the system. Focusing on simplified cross layer design approaches, this volume describes advanced techniques such as adaptive resource management, adaptive modulation and coding, 4G communications, QoS, diversity combining, and energy and mobility aware MAC protocols. The first volume in the series, Adaptive Signal Processing in Wireless Communications (cat no.46012) covers adaptive signal processing at the physical layer.
Author: Praveen Janarthanan
Publisher:
Published: 2013
Total Pages: 44
ISBN-13:
DOWNLOAD EBOOKIt is well known that the modern day wireless networks involve a significant amount of video traffic. The present day physical layer standards support high bit-rates so that the HD video could be streamed. But though the bit-rates are high, sudden channel errors are unexpected and unavoidable. This reflects on the video quality very badly. This means there is still room for intelligent solution for efficient video transfer. Cross-layer approach is one of the solution. Due to presence of frame dependencies in video the frames are prioritized and assigned a relative priority index values which is used to provide unequal error protection. Also the transmission deadlines of each frame is different. Thus a time based adaptive MAC layer re-transmission is proposed in this thesis. In this thesis we mainly focus on developing a cross-layer framework for wireless unicast video transmission on software defined radios (SDR). SDR are being very flexible in implementing MAC and PHY layers, helps to easily implement a cross-layer design too. A MAC layer centric cross-layer approach is adopted here. This approach involves choosing an appropriate modulation scheme with the known knowledge of channel state available from PHY layer at the receiver, and relative priority index (RPI) of each video frame from the application layer and adapting MAC re-transmission based on transmission deadline (Td) of the video packet from APP layer. An in-band cross-layer signaling is adopted here, in which RPI and Td are written in the header of the rtp packet. The SNR values from receiver are sent back to the sender along with the MAC acknowledgment. A content aware time based adaptive re-transmission (TAR) and a heuristic modulation selection algorithm are implemented using this framework. MAC and PHY layers are developed on GNU radio with USRPs N210s. Evalvid tool at the application layer for video streaming and evaluation. Results show that the gain in the efficiency is mostly due to the TAR mechanism.
Author: Harsha Nishantha Deepal Appuhami Ralalage
Publisher:
Published: 2014
Total Pages:
ISBN-13:
DOWNLOAD EBOOKAuthor: Yushi Shen
Publisher: LAP Lambert Academic Publishing
Published: 2010-02
Total Pages: 160
ISBN-13: 9783838343617
DOWNLOAD EBOOKOver the past decades, a tremendous effort has been put into the research to develop advanced system for video communications over wireless and Internet channels. Because video communications are essentially delay-sensitive, bandwidth-intense and loss-tolerant, joint source-channel coding (JSCC) is investigated intensively to attain the optimum performance. The advances achieved in cross-layer design at the lower layers (PHY and DLL) can be further enhanced by taking into account source characteristics and requirements allowing existing networks to provide optimal time-varying Quality of Service (QoS). This book proposes both coding schemes and system design strategies for video wireless communications. The analysis should be especially useful to professionals in video coding and wireless communications fields, both in academia and in industry.
Author: Benny Bing
Publisher: Cambridge University Press
Published: 2008
Total Pages: 847
ISBN-13: 0521895847
DOWNLOAD EBOOKProvides the key practical considerations for deploying wireless LANs and a solid understanding of the emerging technologies.
Author:
Publisher:
Published: 2016
Total Pages: 134
ISBN-13:
DOWNLOAD EBOOKRapid growth of video applications over wireless networks is overwhelming the wireless bandwidth. Since video applications demand large bandwidth and realtime transmission, supporting the rapidly increasing video traffic over the bandwidth-limited, error-prone, and time-varying wireless channels is very challenging. As a result, the video applications are likely to suffer packet losses over wireless networks which results in quality degradation. In this dissertation, we design a distortion prediction model for H.264/AVC compressed video streams, and use it for designing novel cross-layer protocols for enhancing the video quality by making more efficient use of the available wireless resources. The cumulative mean squared error (CMSE) is a widely used measure of video distortion. However, CMSE measurement is a time-consuming and computationally-intensive process which is not suitable for many video applications. A low-complexity and low-delay generalized linear model is proposed for predicting CMSE contributed by the loss of H.264 AVC encoded video slices. The model is trained over a video database by using a combination of video factors that are extracted during the encoding of the current frame, without using any data from future frames in the group of pictures (GOP). The slices are then prioritized within a GOP based on their predicted CMSE values. The accuracy of the CMSE prediction model is analyzed using cross-validation, analysis of variance, and correlation coefficients. The simulations are carried out to evaluate the performance of the CMSE prediction model for varying encoder configurations and bit rates of test videos. The CMSE slice prediction model is used to design an unequal error protection (UEP) scheme, using the rate-compatible punctured convolutional (RCPC) codes over wireless channels. This scheme provides protection to the video slices against the channel errors, based on their priority, in order to minimize the video distortion. An application of our slice prioritization is demonstrated by implementing a priority-aware slice discard scheme, where the low-priority slices are dropped from the router when the network experiences congestion. Additionally, the GOP-level slice prioritization is extended to the frame-level slice prioritization, and its performance is evaluated over the additive white Gaussian noise (AWGN) channels The idea of using slice CMSE prediction is extended to adapt the video packet size to the wireless channel conditions, in order to minimize the video distortion. A real-time, priority-aware joint packet fragmentation and error protection scheme for real-time video transmission over Rayleigh fading channels is presented. The fragment error rates (FERs) are simulated for a combination of different fragment sizes and RCPC code rates. These FERs are then used to determine the optimal fragment sizes and code rates for packets of each priority class by minimizing the expected normalized predicted CMSE per GOP in H.264 video bit stream. An improvement in the received video quality over the conventional and priority-agnostic packet fragmentation schemes is observed. Next, a cross-layer, priority-aware scheduling scheme for real-time transmission of multiple video applications over a time-varying channel is developed. Each video application considered has different characteristics such as user priority, latency, distortion, size, and encoding bit rate. A cost function is optimized to determine the scheduling order for video frames. The performance of our scheme is compared with that of the CMSE based scheme, where the frames are rank-ordered for transmission using its CMSE per bit values, and with the earliest deadline first (EDF) scheme in which each user takes turns to transmit a frame. A collaborative effort with other researchers and developed two additional cross-layer error protection schemes. In the first scheme, a cross layer UEP scheme that jointly assigned FEC at both the Application layer (using Luby Transform) and the Physical layer (using RCPC codes) for prioritized video transmission is developed. The video distortion function is minimized by using the genetic algorithm (GA). The performance of our scheme is evaluated for different channel SNR values. In the second UEP scheme, a framework that combined the RCPC codes and concatenated it with hierarchical quadrature amplitude modulation (QAM) is investigated. Employing RCPC codes and hierarchical modulation jointly resulted in greater flexibility as some parts of the data can be protected only by the hierarchical modulation while others may be protected by a low FEC code rate. The performance of the proposed scheme is compared to the standard 8-QAM with symmetric constellation.
Author: 盧一斌
Publisher:
Published: 2015
Total Pages:
ISBN-13:
DOWNLOAD EBOOKAuthor: Hobin Kim
Publisher:
Published: 2011
Total Pages: 95
ISBN-13: 9781124738512
DOWNLOAD EBOOKWhen we transmit multimedia through wireless channels, we need to protect source bits from channel noise. However, due to the constraints on the channel resources, source and channel bits should share the resources optimally in the sense of distortion or throughput. That is, the problem is how to allocate channel resources such as the bandwidth, diversity, or transmit power to the source and channel under system constraints. In addition, due to the unequal priority of source packets, performance can be improved by assigning unequal channel resources to the packets based on their priority. In this dissertation, we introduce an information-theoretic framework which allows us to analyze the system performance mathematically with unequal allocation of the channel resources with respect to the unequal priority of the source packets. By applying the information theoretic framework, an algorithm to find the throughput-optimal unequal error protection (UEP) is derived. The first example to apply this framework is the progressive image transmission over block fading channels with relay-assisted distributed spatial diversity. Assuming a progressive image coder with a constraint on the transmission bandwidth, we formulate a joint source-channel rate allocation scheme that maximizes the expected source throughput. Specifically, using Gaussian as well as BPSK inputs on at Rayleigh fading channels, we lower bound the average packet error rate by the corresponding mutual information outage probability, and derive the average throughput expression as a function of channel code rates as well as channel signal-to-noise ratio (SNR) for a frequency-division multiplexing-based system both without relaying and with a half-duplex relay using a decode-and-forward protocol. At high SNR, the optimization problem involves a convex function of the channel code rates, and we show that a known recursive algorithm can be used to predict the performance of both systems. The second example is the layered transmission of a Gaussian source over multiple relays using superposition coding. At first, we analyze the outage probability and performance in terms of average throughput and distortion for decodeand-forward (DF) protocols with single-layer and superposed two-layer coding. For the superposition coding approach, we consider different power allocations to the base and enhancement layers. Then, we propose a simple protocol which assigns a pre-determined number of relays to individual layers instead of repeating the superposition coded packet at the relay. We also present numerical results based on the analysis to compare the performance. We then consider a practical application where motion compensated fine granular scalable (MC-FGS) video is transmitted over multi-input multi-output (MIMO) wireless channels and the leaky and partial prediction schemes are applied in the enhancement layer of MC-FGS video to exploit the tradeoff between error propagation and coding efficiency. For reliable transmission, we propose UEP by considering a tradeoff between reliability and data rates, which is controlled by forward error correction (FEC) and MIMO mode selection to minimize the average distortion. In a high Doppler environment where it is hard to get an accurate channel estimate, we investigate the performance of the proposed MC-FGS video transmission scheme with joint control of both the leaky and partial prediction parameters and the UEP. In a slow fading channel where the channel throughput can be estimated at the transmitter, adaptive control of the prediction parameters is considered.