Unequal Error Protection Scheme Research Articles

Multiview coding and error correction coding for 3D video over noisy channels

We consider the joint source–channel coding problem of stereo video transmitted over AWGN and flat Rayleigh fading channels. Multiview coding (MVC) is used to encode the source, as well as a type of spatial scalable MVC. Our goal is to minimize the total number of bits, which is the sum of the number of source bits and the number of forward error correction bits, under the constraints that the quality of the left and right views must each be greater than predetermined PSNR thresholds at the receiver. We first consider symmetric coding, for which the quality thresholds are equal. Following binocular suppression theory, we also consider asymmetric coding, for which the quality thresholds are unequal. The optimization problem is solved using both equal error protection (EEP) and a proposed unequal error protection (UEP) scheme. An estimate of the expected end-to-end distortion of the two views is formulated for a packetized MVC bitstream over a noisy channel. The UEP algorithm uses these estimates for packet rate allocation. Results for various scenarios, including non-scalable/scalable MVC, symmetric/asymmetric coding, and UEP/EEP, are provided for both AWGN and flat Rayleigh fading channels. The UEP bit savings compared to EEP are given, and the performances of different scenarios are compared for a set of stereo video sequences.

Compressed sensing‐based unequal error protection by linear codes

In many wireless communication systems, data can be divided into different importance levels. For these systems, unequal error protection (UEP) techniques are used to ensure lower bit error rate for the more important classes. Moreover, if the precise characteristics of the channel are known, UEP can be used to correctly recover the more important classes even under severe receiving conditions. In this study, a UEP scheme based on compressed sensing via a linear program is proposed. Discrete wavelet transform (DWT) is chosen as the sparsifying basis, and then DWT-coded information is divided into two-layered coded streams, each of which is transmitted differentially by applying an unequal number of information bits in linear codes according to the time-varying characteristic of the corrupted channel. In this proposed transmission scheme, the more important information is to guarantee error-free transmission. At the decoder, one can simply reconstruct the signal via the l 1-minimisation algorithm. Simulation results show that the proposed scheme can achieve a higher peak signal-to-noise ratio (PSNR) and obviously improve the error resilience compared to the equal error protection scheme and other UEP methods. More importantly, with the increase of channel corrupted ratio, the drop rate of PSNR is much slower than other solutions. It indicates that the proposed method has better robustness for severe channel conditions.

Cross-Layer Forward Error Correction Scheme Using Raptor and RCPC Codes for Prioritized Video Transmission Over Wireless Channels

The unequal error protection (UEP) has shown promising results for transmitting video over error-prone wireless channels. In this paper, we investigate the cross-layer design of forward error correction (FEC) schemes by using the UEP Raptor codes at the application layer (AL) and UEP rate compatible punctured convolutional (RCPC) codes at physical layer (PHY) for prioritized video packets. The video packets are prioritized based on their contribution to the received video quality. A genetic algorithm (GA)-based optimization algorithm is proposed to find the optimal parameters for both Raptor and RCPC codes, to minimize the video distortion and maximize the peak signal-to-noise-ratio for the given video bit rates and channel constraints (i.e., SNR and available bandwidth). We evaluate the performance of four combinations of the UEP schemes for H.264/AVC encoded video sequences over the AWGN and Rayleigh fading channels and show the superiority of the optimized cross-layer UEP FEC scheme. For Rayleigh fading channel, the proposed cross-layer optimization uses two different time-scales at AL and PHY which allows PHY to adapt faster to the changing channel quality.

Hybrid FLUTE/DASH video delivery over mobile wireless networks

ABSTRACTThis paper describes how File Delivery over Unidirectional Transport (FLUTE) and Dynamic Adaptive Streaming over Hypertext Transfer Protocol (DASH) can be used to provide mobile video streaming services over broadcast wireless networks. FLUTE is a multicast protocol for multimedia file download. In this proposal, the protocol is adapted to provide video streaming services in crowded environments. Thus, video is delivered over a single connection to all viewers, reducing the traffic in the network. FLUTE incorporates an application‐layer forward error correction (AL‐FEC) mechanism in order to improve the reliability of the broadcast communication channel. For streaming applications, AL‐FEC improves the relationship between the peak signal‐to‐noise ratio (PSNR) of the received video and the bandwidth allocated to the broadcast connection. The AL‐FEC hereby presented applies simple unequal error protection schemes to favour the download of key frames. Furthermore, the proposal is based on the same video segmentation mechanism as DASH, and therefore, clients can connect to a DASH repository to repair errors in the segments. This paper shows that FLUTE and DASH can be seamlessly integrated into a hybrid broadcast/unicast streaming technology, providing flexibility to trade off PSNR and bandwidth depending on the conditions of the mobile network. Copyright © 2014 John Wiley & Sons, Ltd.

Robust Transmission of prioritized H.264/AVC employing linear block codes and non-uniform 8PSK modulation for wireless communications

Due to the fruitful and diversified contents of multimedia traffic and the vulnerable environment of wireless communications, applying unequal error protection (UEP) is now an active research topic. In this paper, we present a novel and alternative method of providing UEP by combining the channel code with the modulation-assisted symbol. We use the powerful BCH code and non-uniform 8PSK modulation to handle UEP of the prioritized H.264/AVC bit stream. Based on the non-uniformly distributed property of the importance of intracoded (I-frame) and the predictive coded frame (p-frame), we have found a suitable approach for the non- uniform 8PSK signal constellation. Simulation results show that our proposed UEP scheme is able to significantly improve the peak signal-to-noise ratio (PSNR). It has been shown that at a value of Eb/No of 14 dB the video sequence transmitted at a bit rate of 512 Kbps yields a 4 dB gain in PSNR compared with the uniform 8PSK modulation case which makes the proposed UEP scheme robust to wireless communication errors.

FPGA Implementation of MIMO System using Xilinx System for Video Transmission

In this paper, we have introduced an architecture for real-time video transmission over multiple- input multiple-output (MIMO) wireless communication systems. We employ the 2x1 and 2x2 Alamouti MIMO technique to develop a transmission system and implement the design on FPGA using Xilinx System using the modeling and simulation capabilities of MATLAB. Furthermore, according to the contribution to the reconstructed video quality, we apply unequal error protection strategy using STBC space-time codes for each video bitstream. We present a solution using FPGA as target platform (instead of software), for implementing algorithms for transmission of educational videos using MIMO systems. In our proposed system, we have provided the system performance of a joint MPEG-2 coding scheme with convolutional channel coding and space time block coding (STBC) techniques, associated with suitable modulation method (QAM and BPSK), for video data transmission over a wireless MIMO system with Rayleigh fading noises. Simulation results show the quality of the reconstructed image can be significantly improved over only using space time coding. The comparison has been done on the basis of quality of reproduced image by measuring image PSNR based on SNR and BER value for different system model is realized over Xilinx Virtex-4 XC4VFX100FFG1517-11C FPGA based WRAP board. Keywords: FPGA (Field Programmable Gate Arrays); STBC (Space Time Block Coding), Bit error rate(BER), FPGA, Peak to signal noise ratio (PSNR), Multiple input multiple output (MIMO), WRAP board, Joint source channel coding, Space time block coding(STBC).

Video Error Concealment Using a Computation-Efficient Low Saliency Prior

Error concealment in packet-loss-corrupted streaming video is inherently an under-determined problem, as there are insufficient number of well-defined criteria to recover the missing blocks perfectly. When a Region-of-Interest (ROI) based unequal error protection (UEP) scheme is deployed during video streaming-i.e., more visually salient regions are strongly protected-a lost block is likely to be of low saliency in the original frame. In this paper, we propose to add a low-saliency prior to the error concealment problem as a regularization term. It serves two purposes. First, in ROI-based UEP video streaming, low-saliency prior provides the correct side information for the client to identify the correct replacement blocks for concealment. Second, in the event that a perfectly matched block cannot be unambiguously identified, the low-saliency prior reduces viewer's visual attention on the loss-stricken region, resulting in higher overall subjective quality. We study the effectiveness of a low-saliency prior in the context of a previously proposed RECAP error concealment system. RECAP transmits a low-resolution (LR) version of an image alongside the original high-resolution (HR) version, so that if blocks in the HR version are lost, the correctly-received LR version can serve as a template for matching of suitable replacement blocks from a previously correctly-decoded HR frame. We add a low-saliency prior to the block identification process, so that only replacement candidate blocks with good match and low saliency can be selected. Further, we develop a low-complexity convex approximation to the well known Itti-Koch-Niebur saliency model, which enables the low-saliency error concealment problem to be solved efficiently. Experimental results show that: i) PSNR of the error-concealed frames can be increased dramatically (up to 3.6 dB over the original RECAP), showing the effectiveness of a low-saliency prior in the under-determined error concealment problem; and ii) subjective quality of the repaired video using our proposal, as confirmed by an extensive user study, is better than the original RECAP.

Integrating Non-Repetitive LT Encoders With Modified Distribution to Achieve Unequal Erasure Protection

The performance of LT code is highly related to the code length. A decoder is more likely to deplete degree-1 encoding symbols and terminate during early stage when the code length is short. In this work, we modify the robust Soliton distribution (RSD) and increase the degree-1 proportion. More degree-1 encoding symbols can be generated to relieve early decoding termination. The proportion of low degrees, except for degree-1, is also reduced. Therefore, receivers collect less encoding symbols carrying redundant information. In addition, Non-Repetitive (NR) encoding scheme is proposed to avoid producing repeated degree-1 encoding symbols. To improve video transmission quality, previous studies redesign LT codes to provide Unequal Error Protection (UEP) for different Scalable Video Coding (SVC) layers. Unlike those studies to modify the code structure, we integrate multiple NR encoders to achieve UEP ability. Experimental results show that our UEP scheme outperforms previous studies in terms of the PSNR.

Scene content driven FEC allocation for video streaming

Unequal error protection schemes applied on video data streams, considering varying importance of data packets over a group of pictures (GOP), are more efficient in terms of rate-distortion performance at different loss rates. Importance ordering policy adopted so far, mostly considered frame positions within a GOP. In the present work, we offer significant importance to the packets containing scene-transition frames, as these should be better error protected. We adopt a strategy of Forward Error Correcting (FEC) Code allocation, based on the minimization of end-to-end distortion up to the decoder, assuming that error concealment is adopted at the decoder. Two FEC allocation strategies are proposed within the Block of Packets (BOP) structure — one is an iterative modified hill climbing approach and the other is a reduced complexity heuristic approach. The Gilbert–Elliot model is used for the modeling of transmission channel. The proposed FEC allocation schemes outperform existing FEC allocation schemes in terms of PSNR for sequences with and without transitions, when transmitted over lossy channels.

Inter-Layer FEC Aided Unequal Error Protection for Multilayer Video Transmission in Mobile TV

Layered video coding creates multiple layers of unequal importance that enables us to progressively refine the reconstructed video quality. When the base layer (BL) is corrupted or lost during transmission, the enhancement layers (ELs) must be dropped, regardless of whether they are perfectly decoded or not, which implies that the transmission power assigned to the ELs is wasted. In this treatise, we propose an inter-layer forward error correction (FEC) coded video transmission scheme for mobile TV. At the transmitter, the proposed interlayer (IL) coding technique implants the systematic information of the BL into the ELs by using exclusive-OR operations. At the receiver, the implanted bits of the ELs may be utilized for assisting in decoding the BL. Furthermore, the data partition mode of H.264 video coding is utilized as the source encoder, where the type B and type C partitions will assist in protecting the type A partition. The IL coded bitstream will then be modulated and transmitted over a multifunctional multiple input multiple output (MF-MIMO) scheme for the sake of improving the system's performance in mobile environments. The proposed system may be readily combined with the traditional unequal error protection (UEP) technique, where extrinsic mutual information (MI) measurements are used for characterizing the performance of our proposed technique. Finally, our simulation results show that the proposed system model outperforms the traditional UEP aided system by about 2.5 dB of E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> /N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> or 3.4 dB of peak signal-to-noise ratio (PSNR) at the cost of a 21% complexity increase, when employing a recursive systematic convolutional code. Furthermore, unlike the traditional UEP strategies, where typically stronger FEC-protection is assigned to the more important layer, employing our proposed IL coding technique requires weaker FEC to the more important layer. For example, the system relying on channel coding rates of 0.85, 0.44, and 0.44 for the type A, type B, and type C H.264 video partitions, respectively, achieves the best system performance when employing a recursive systematic convolutional (RSC) code.

Hierarchical modulated quadrature amplitude modulation with signal space diversity and maximal ratio combining reception in Nakagami‐ m fading channels

This study combines hierarchical modulation with signal space diversity (SSD) to present an unequal error protection scheme with improved bit-error rate (BER) performance for single as well as multiple antenna reception by employing maximal ratio combing in Nakagami- m fading channels. The optimal rotation angles for different constellation priority parameter α are derived. A theoretical BER expression in Nakagami- m fading channels using the nearest neighbour approximation approach is also derived. This is confirmed as a valid performance approximation for single and multiple antenna reception through simulations. The resultant scheme produces improved BER performance for both important and less important data without consuming any additional power than a non-SSD system at the cost of increased complexity at detection. Specifically, performance gains of up to 18 and 17 dB at a BER of 1 × 10 -5 for base and refinement bits, respectively, are observed for single receive antenna with Nakagami m = 1. A further improvement of roughly 3 dB at a BER of 1 × 10 -6 for base bits at N = 3 receiver antennas is found as hierarchy is increased. Although the gain is observed to decrease as m increases, a gain of 14 dB at 1 × 10 -6 for α = 4 is achieved even as m increases from m = 1 to m = 3.

A Cross-Layer Unequal Error Protection Scheme for Prioritized H.264 Video using RCPC Codes and Hierarchical QAM

We investigate the rate-compatible punctured convolutional (RCPC) codes concatenated with hierarchical QAM for designing a cross-layer unequal error protection scheme for H.264 coded sequences. We first divide the H.264 encoded video slices into three priority classes based on their relative importance. We investigate the system constraints and propose an optimization formulation to compute the optimal parameters of the proposed system for the given source significance information. An upper bound to the significance-weighted bit error rate in the proposed system is derived as a function of system parameters, including the code rate and geometry of the constellation. An example is given with design rules for H.264 video communications and 3.5-4 dB PSNR improvement over existing RCPC based techniques for AWGN wireless channels is shown through simulations.

A Novel Turbo Unequal Error Protection Scheme for Image Steganography

An Unequal Error Protection (UEP) scheme for image steganography is proposed in this paper. When stego images are transmitted through a noisy channel, the embedded message may be more sensitive to noise than the cover message. Therefore, we propose a Turbo UEP coding scheme for steganographic communication in a noisy channel, which provides higher error protection for the embedded message and lower error protection for the cover message. Simulations show that this coding scheme provides different error protection levels in one coding process and maintains the coding rate constant. In addition, an application scheme of the proposed Turbo UEP code for steganographic communication is presented, and the experimental results show that the extracted secret images have better quality than the cover images after decoding.

Techniques for Compensating Memory Errors in JPEG2000

This paper presents novel techniques to mitigate the effects of SRAM memory failures caused by low voltage operation in JPEG2000 implementations. We investigate error control coding schemes, specifically single error correction double error detection code based schemes, and propose an unequal error protection scheme tailored for JPEG2000 that reduces memory overhead with minimal effect in performance. Furthermore, we propose algorithm-specific techniques that exploit the characteristics of the discrete wavelet transform coefficients to identify and remove SRAM errors. These techniques do not require any additional memory, have low circuit overhead, and more importantly, reduce the memory power consumption significantly with only a small reduction in image quality.

Dual Diversity Space-Time Coding for Multimedia Broadcast/Multicast Service in MIMO Systems

Multimedia Broadcast/Multicast Service (MBMS) is a bandwidth efficient broadcast scheme for multimedia communications. To support prioritized transmissions, the unequal error protection (UEP) for multi-resolution multimedia sources can be realized through MBMS. Nevertheless, the enhancement on the transmission fidelity in base layer typically sacrifices the fidelity of enhancement layers. Herein, a novel dual diversity space-time coding (DDSTC) is proposed to exploit the intrinsic UEP capability of space-time codes by utilizing a constellation mapping duo for two consecutive transmission periods in multiple-input multiple-output (MIMO) systems. As compared with Alamouti coding, the DDSTC achieves coding gains on the transmission error rates of base layer without significant degradations on the enhancement layers. At the transmission rates of base and enhancement layers equal to 2 bits per transmission, the DDSTC obtains 1.3 dB and 3.0 dB coding gains for base layer in 2 × 2 and 2 × 3 MIMO systems respectively. Besides, analytical analysis on symbol error probabilities verifies that 6 dB asymptotic coding gain is reachable in rich transmit diversity scenarios. While attaining the considerable improvements on error rates, the DDSTC avoids the high decoding complexity by adopting our proposed decoding schemes. Simulation results show that DDSTC outperforms conventional UEP schemes based on hierarchical modulations or power allocations.

A novel unequal error protection scheme for 3-D video transmission over cooperative MIMO-OFDM systems

Currently, there has been intensive research to drive three-dimensional (3-D) video technology over mobile devices. Most recently, multi-input multi-output (MIMO) with orthogonal frequency division multiplexing (OFDM) and cooperative diversity have been major candidates for the fourth-generation mobile TV systems. This article presents a novel unequal error protection (UEP) scheme for 3-D video transmission over cooperative MIMO-OFDM systems. Several 3-D video coding techniques are investigated to find the best method for 3-D video transmission over the error-prone wireless channels. View plus depth (VpD) has been found the best technique over other techniques such as simulcast coding (SC) and mixed-resolution stereo coding (MRSC) in terms of the performance. Various UEP schemes are proposed to protect the VpD signals with different importance levels. Seven video transmission schemes for VpD are proposed depending on partitioning the video packets or sending them directly with different levels of protection. An adaptive technique based on a classified group of pictures (GoP) packets according to their protection priority is adopted in the proposed UEP schemes. The adaptive method depends on dividing GoP to many packet groups (PG’s). Each PG is classified to high-priority (HP) and low-priority (LP) packets. This classification depends on the current signal-to-noise ratio (SNR) in the wireless channels. A concatenating form of the rate-variable low-density parity-check (LDPC) codes and the MIMO system based on diversity of space-time block codes (STBC) is employed for protecting the prioritized video packets unequally with different channel code rates. For channel adaptation, the switching operations between the proposed schemes are employed to achieve a tradeoff between complexity and performance of the proposed system. Finally, three protocols for 3-D video transmission are proposed to achieve high video quality at different SNRs with the lowest possible bandwidth.

Unequal error protection scheme based hierarchical 16-QAM for 3-D video transmission

In this paper, an unequal error protection (UEP) scheme based on hierarchical quadrature amplitude modulation (HQAM) for three-dimensional (3-D) video transmission is proposed. The proposed scheme exploits unique characteristics of the color plus depth map stereoscopic video, where the color sequence has a more significant impact on the reconstructed video quality. The UEP scheme assigns more protection to the color sequence than the depth map so as to achieve high quality 3-D video. Different levels of protection are assigned through hierarchical 16-QAM. The color data with high priority (HP) are mapped onto the most significant bits (MSBs) of the 16- QAM constellation points and the depth map with low priority (LP) are mapped onto the less significant bits (LSBs). Simulation results demonstrate that the proposed UEP scheme outperforms the conventional equal error protection (EEP) schemes by up to 5 dB in terms of the received left and right views quality.

Unequal Error Protection Based on DVFS for JSCD in Low-Power Portable Multimedia Systems

This article presents a low-power decoder design for joint source-channel decoding (JSCD) based on a novel unequal error protection (UEP) scheme over additive white gaussian noise (AWGN) channels. Conventional JSCD schemes, adopting low-density parity check (LDPC) codes for multimedia devices, typically operate at a fixed-time decoding loop, regardless of the quality of data received. We present a JSCD scheme that achieves reduction in power through minimum energy decoding and dynamic voltage and frequency scaling (DVFS). Consequently, up to 39% power reduction is achieved in Foreman, Akiyo, and Mobile video streams without performance degradation in reconstructed video quality.

Unequal error correction strategy for magnetic recording systems with multi-track processing

In multi-track detection, the simultaneous recovery of user data of all tracks is obtained from multi-head or single-head reader with buffer. Due to incomplete inter-track interference (ITI) information of the outer tracks, unequal error rates exist among tracks. For a system with three-track processing, the center track exhibits a better performance than the others. In this work, we propose the unequal error protection (UEP) schemes to improve the overall system performance of a 2-D interference bit-patterned recording system with multi-track detection. The performances of the proposed schemes are investigated for the BPM channels with and without the media noise. Based on the simulation results, the proposed schemes offer the gain of about 0.2–0.3 dB over the equal error protection (EEP) scheme at a bit error rate of 10−4.

Assurance of Energy Efficiency and Data Security for ECG Transmission in BASNs

With the technological advancement in body area sensor networks (BASNs), low cost high quality electrocardiographic (ECG) diagnosis systems have become important equipment for healthcare service providers. However, energy consumption and data security with ECG systems in BASNs are still two major challenges to tackle. In this study, we investigate the properties of compressed ECG data for energy saving as an effort to devise a selective encryption mechanism and a two-rate unequal error protection (UEP) scheme. The proposed selective encryption mechanism provides a simple and yet effective security solution for an ECG sensor-based communication platform, where only one percent of data is encrypted without compromising ECG data security. This part of the encrypted data is essential to ECG data quality due to its unequally important contribution to distortion reduction. The two-rate UEP scheme achieves a significant additional energy saving due to its unequal investment of communication energy to the outcomes of the selective encryption, and thus, it maintains a high ECG data transmission quality. Our results show the improvements in communication energy saving of about 40%, and demonstrate a higher transmission quality and security measured in terms of wavelet-based weighted percent root-mean-squared difference.