Unequal Error Protection Scheme Research Articles

Efficient unequal error protection for online fountain codes

In this paper, an efficient unequal error protection (UEP) scheme for online fountain codes is proposed. In the buildup phase, the traversing-selection strategy is proposed to select the most important symbols (MIS). Then, in the completion phase, the weighted-selection strategy is applied to provide low overhead. The performance of the proposed scheme is analyzed and compared with the existing UEP online fountain scheme. Simulation results show that in terms of MIS and the least important symbols (LIS), when the bit error ratio is 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−4</sup> , the proposed scheme can achieve 85% and 31.58% overhead reduction, respectively.

New Unequal Error Protection Strategy for Image Transmission Based on Bilayer-Lengthened PLDPC Code in Half-Duplex Relay System

To reduce the waste of energy in communications, unequal error protection (UEP) is used to provide asymmetric protection for messages with different levels of importance. This paper proposes new efficient strategies of UEP based on bilayer protograph-based low-density parity check (PLDPC) codes in decoding-and-forward (DF) relay systems. In particular, we jointly utilize source coding and channel coding to design UEP strategies and then save transmission energy. According to the different levels of importance of discrete cosine transform (DCT) coefficients of image and variance statistical characteristics of image sub-blocks, bilayer-lengthened PLDPC codes are exploited to protect the transmitted image information with different importance levels at the half-duplex relay system. In the end, the simulation result shows that the proposed UEP schemes achieve excellent performance gains compared to conventional equal error protection (EEP) scheme. Additionally, the complexity analysis of the UEP strategies is given.

Unequal error protection transmission for federated learning

Communication has been recognized as one of the primary challenges of federated learning (FL), but the actual communication algorithm or protocol design is still rarely involved in the existing studies. In the paper, viewing the model exchange in FL as a special kind of traffic, an unequal error protection (UEP) scheme is designed based on multi-rate channel coding and multi-layer modulation for it. To answer the question of how to make error control for FL when the wireless channel is no longer simplified as a pipeline, this paper firstly theoretically analyzes the impact of transmission error on machine leanring (ML) model, which reveals that the dynamic range of the weights should be taken into consideration. Guided by the analysis, the UEP scheme is applied to FL in multiple perspectives including parameter, network and time. Furthermore, a UEP-based adaptive coding method is developed for the case with dynamic signal-to-noise ratio (SNR) to ensure faster and more stable convergence of the FL model while saving as much bandwidth as possible. Comprehensive numerical simulation on several real-world datasets verifies that the proposed UEP transmission schemes can indeed bring significant benefits in accuracy, robustness and efficiency, especially when the channel condition is poor.

Guest editorial: Smart communications and networking: architecture, applications, and future challenges

Guest editorial: Smart communications and networking: architecture, applications, and future challenges

Cross-layer unequal error protection using 64-HQAM and RCPT codes for robust image communication

In unequal error protection (UEP) schemes, the bits are protected according to their significance in terms of distortion reduction capability during the reconstruction process. The conventional UEP schemes are primarily designed either using forward error correction at application layer of network architecture, or hierarchical modulation at the physical layer. In this paper, an optimized cross-layer UEP scheme for set partitioning in hierarchical trees coded images is investigated. The proposed scheme uses rate compatible punctured turbo codes at application layer and two-layered 64-hierarchical QAM (64-HQAM) at physical layer. Simulation results show that proposed cross-layer UEP performs slightly better than application layer’s optimized turbo coding for additive white Gaussian noise channel but performs significantly better in flat Rayleigh fading channel, specifically under poor channel conditions. The proposed scheme is highly bandwidth efficient having the robustness performance close to that of the scheme using hierarchical 4-PAM (H 4-PAM). Complexity analysis of the proposed solution has been carried out.

A Polar Codes‐Based Distributed UEP Scheme for the Internet of Things

The Internet of Things (IoT), which is expected to support a massive number of devices, is a promising communication scenario. Usually, the data of different devices has different reliability requirements. Channel codes with the unequal error protection (UEP) property are rather appealing for such applications. Due to the power‐constrained characteristic of the IoT services, most of the data has short packets; therefore, channel codes are of short lengths. Consequently, how to transmit such nonuniform data from multisources efficiently and reliably becomes an issue be solved urgently. To address this issue, in this paper, a distributed coding scheme based on polar codes which can provide UEP property is proposed. The distributed polar codes are realized by the groundbreaking combination method of noisy coded bits. With the proposed coding scheme, the various data from multisources can be recovered with a single common decoder. Various reliability can be achieved; thus, UEP is provided. Finally, the simulation results show that the proposed coding scheme is viable.

Low-Power Cross-Layer Error Management Using MIMO-LDPC Iterative Decoding for Video Processing

This paper presents a novel low-power joint decoding system composed of a multiple-input multiple-output (MIMO) detector, low-density parity-check (LDPC) channel decoder, and H.264 source decoder for energy-aware and cross-layer source-channel transmission systems. Our aim is to achieve a minimum power design that meets the expected quality of service (QoS) at the application layer. This design includes an iterative MIMO-LDPC decoder for minimizing communication errors and an unequal error protection scheme for reducing energy consumption in transmission. The experiment results reveal that our proposed iterative MIMO-LDPC-H.264 joint decoder achieved up to 66% energy reduction with only 0.09 dB peak signal-to-noise ratio degradation when compared to a non-UEP based joint source-channel decoding system.

Scalable Panoramic Wireless Video Streaming Relying on Optimal-Rate FEC-Coded Adaptive QAM

The demanding bitrate requirements of supporting flawless streaming of immersive video remains a challenge. To minimize the bandwidth without degrading the user's experience, we may opt for partitioning the panoramic video frame into numerous tiles and only transmit those covered by the predicted Field of View (FoV), but naturally, this philosophy critically hinges on the accuracy of the Head Movement Prediction (HMP). However, since the HMP is never 100% accurate, rebuffering of the missing portions due to misprediction is likely to introduce video freezes or artefacts, which may significantly degrade the users’ experience. Hence, instead of only transmitting the FoV tiles, Scalable Video Coding (SVC) comes to rescue. Explicitly, in SVC schemes, multiple layers having different importance provide a promising solution, where the basic quality of the entire panoramic video is supported by the Base Layer (BL) that only requires a low bitrate, while the Enhancement Layers (EL) are invoked for enhancing the quality of the predicted FoV. In this treatise, we propose coding rate adaptation assisted near-instantaneously Adaptive Quadrature Amplitude Modulation (AQAM) for layered panoramic video streaming. In our design, we categorize the video streaming into three priority classes according to the FoV and the SVC layer index, each of which is mapped to the most appropriate modulation mode determined by the instantaneous channel quality. Furthermore, we conceive an Evolutionary Algorithm (EA) assisted Forward Error Correction (FEC) coding rate optimization method for providing Unequal Error Protection (UEP) in order to maximize the uncoded source-rate according to the inter-frame and inter-layer decoding dependency for tile-based panoramic video streaming. The simulation results show that the proposed AQAM assisted UEP scheme configured by our EA assisted coding rate optimization algorithm significantly improves the overall video performance compared to its Equal Error Protection (EEP) counterpart, and provides perceptually pleasing video quality across a wide range of channel conditions by selecting the most appropriate modulation mode based on the instantaneous channel Signal-to-Noise Ratio (SNR).

Design and implementation of a novel unequal error protection scheme for coded MIMO systems

Mobile and wireless technologies such as Wi-Fi, WiMAX, 3G, 4G/LTE and the emerging 5G require communication of high quality videos with the limited available bandwidth. H.264/AVC and High Efficiency Video Coding (HEVC) or H.265 multimedia standards are implemented in these technologies to fulfill this requirement. Moreover, these standards achieve high error performance over wireless channels and large compression efficiency thereby optimizing channel bandwidth. Multimedia standards employ multi-class bitstreams where unequal levels of importance are assigned to the multimedia content. Consequently, the multi-class bit streams employ Unequal Error Protection (UEP) techniques to achieve optimal redundancy as well as better multimedia error performance and coding gains over wireless channels.Recently, coded Multiple-Input Multiple-Output (MIMO) systems employing Orthogonal Space-Time Block Codes (OSTBCs) have been adopted in mobile and wireless networks with the aim of maximizing spatial diversity gain without sacrificing the channel bandwidth. The problem of establishing reliable wireless communication links with high spatial diversity and coding gains for recent and future networks is a big challenge for researchers. A thorough literature survey reveals that the transmission of HEVC multi-class coded data streams over wireless channels employing coded MIMO systems to achieve both spatial diversity and coding gains has not been explicitly explored. To this end we propose, in this paper, to evaluate the error performance of Multiple-Input Multiple-Output (MIMO) systems employing Orthogonal Space-Time Block Codes (OSTBC) and Hierarchical 4/MQAM Modulation to promote unequal error protection of the coded data. The approach adopted provides excellent unequal error protection capabilities through the hierarchically modulated symbol and both diversity as well as coding gains are achieved. The proposed MIMO systems are designed and implemented in MATLAB Simulink® 2017 and error performances are evaluated through simulations. Experimental results show at a Bit Error Probability (BEP) of 10−4 a coding gain of around 10 dB can be observed between the base and refinement sub-channels with the 2x2 Alamouti code.

Error Performance Analysis of an Unequal Error Protection System for the JPEG 2000 and H.265 Standards Over Wireless Channels

In this paper an unequal error protection scheme based on Rate-Compatible Punctured Convolutional codes employing Hierarchical PSK modulation is presented. New error bounds are derived and reported for AWGN and flat Rayleigh fading channels. Both soft and hard decision decoding techniques are considered in our analysis. The proposed scheme does not involve increased in complexity of resources and bandwidth expansion either. It is shown that by varying the signal to noise ratio and a specific constellation parameter set, which controls the level of error protection, significant error performance can be achieved over the uniform modulation case. All the established theoretical upper bounds are illustrated with numerical examples and these are also simulated using Matlab Simulink® 2017. Simulation results show that near-13-dB difference is achieved between the first and last priority sub-channels of the UEP communication system. The proposed scheme can find suitable applications in digital video broadcasting and Wireless JPEG2000 as well as H.265 data transmission systems.

Efficient Unequal Error Protection Techniques for Tile-Based Transmission of HEVC Videos

The video bitstream compressed by the efficient high efficiency video coding (HEVC) standard is extremely vulnerable to the channel error. For robust transmission of such compressed videos, techniques can be formed based on the specific characteristics of the compression standard. With the introduction of new coding features in HEVC, such as flexible block partitioning and tiles, unequal error protection (UEP) schemes are proposed in this paper aiming to enhance the quality of the important regions. The proposed algorithms are implemented in two and three-levels. For the two-level UEP, tiles are prioritized based on their motion density, which is defined as the ratio of motion vector magnitudes to the block size in a compressed video frame. Furthermore, a three-level UEP is proposed to improve the protection of low-important tiles, which may include moving objects. For this purpose, clustering algorithms, utilizing kernel density estimation (KDE) and density-based spatial clustering of applications with noise (DBSCAN), are modified based on the motion density of coding tree units (CTUs). Indeed, this represents implementation of an object detection algorithm based in compressed domain. Simulation results confirm that proposed UEP schemes achieve better objective quality compared to conventional UEP and equal error protection (EEP) approaches.

An application layer forward error correction method of wireless network broadcasting communication for smart video surveillance system

Aiming at the wireless channel in which the state of video surveillance communication network changes dramatically, to ensure the video impact under a restricted channel bandwidth condition, an application layer forward error correction system for wireless video communication is proposed. This scheme is an improved forward error correction algorithm. The most appropriate redundancy amount is implemented for each FEC block by constantly altering the redundancy in FEC blocks. Firstly, the system describes and implements the optimum video transmission. Then, the RCPC code and Raptor code are used as forward error correction codes in physical layer and application layer respectively, in this way, the optimal system solution can be acquired. In the forward error correction technology, a feedback mechanism is then developed between the receiver and the sender, which will acknowledge that the receiver can extract the packet loss rate from the received speech signal in the current network state in real time, and then the packet loss rate will be transferred back to the sender by the feedback mechanism. The sender can modify the forward packet loss rate according to the packet loss rate. The error-correcting schema can help the next speech signal have the most appropriate forward error-correcting redundancy, reducing bandwidth waste, significantly improving the adaptability and efficiency of forward error-correcting technology in the wireless network. The simulation results show that the average video quality of the proposed scheme is 0.5–4 dB higher than that of the equal error protection scheme and the extended window unequal error protection scheme.

Underwater Image Transmission Using Spatial Modulation Unequal Error Protection for Internet of Underwater Things.

A spatial modulation (SM) scheme has been developed as a hopeful candidate for spectral and energy-efficient wireless communication systems, as it provides a great judgment for the system performance, data transmission rate, receiver complexity, and energy/spectrum efficiency. In SM, the data is conveyed by both habitual M-ary signal constellations and the transmit antennas indices. Therefore, the system data rate improvement due to the side information bits transmitted, encapsulated in indices of the transmit antennas, improves the SM transmission efficiency compared to the different MIMO players. The information bits transmitted over the antenna index and data symbol constellation using M-ary signal performance have different levels of bit error rate (BER) performance. This paper proposes unequal error protection (UEP) scheme for image transmission over the Internet of Underwater Things (IoUTs) using SM. The Set Partitioning in Hierarchical Trees (SPIHT) coders encode the underwater image and classify the encoded bits in two categories: critical and uncritical bits. The critical bits are transmitted over the SM index bits and have a low BER while the uncritical bits are transmitted over high order M-ary signal constellation to resolve the underwater acoustic channel bandwidth limitation problem. The proposed SM-UEP technique has been developed carefully with enough justification and evaluation over the measured underwater acoustic channel and the simulated channel. The simulation results show that the proposed SM-UEP can increase the average peak signal-to-noise ratio (PSNR) of the reconstructed received image considerably, and significantly.

Efficient Mobile Video Streaming via Context-Aware RaptorQ-Based Unequal Error Protection

Mobile video streaming systems typically apply the forward error correction (FEC) at the application layer to cope with packet-level transmission errors, which complements the bit-level correction mechanisms at the physical layer. However, most existing works fail to exploit the block-level dependencies in both intra and interframe coding modes of a single-layer compressed video, and thus are less efficient for the prevailing H.264/AVC and/or H.265/HEVC compatible single-layer video application. To this end, we propose a low-complexity FEC, i.e., context-aware RaptorQ (CA-RQ) with unequal error protection (UEP), to improve the error recovery performance of the single-layer mobile video streaming, through incorporating the block-level dependencies in the compressed video data. We use a packet-level video transmission distortion model that considers the dependencies in both spatial and temporal domains, to quantify the importance of video packets within a group of pictures (GoP). The compressed video packets are categorized and grouped into several classes according to their importance to construct the CA-RQ code with the UEP property. We provide a theoretical analysis on redundancy allocation bounds to demonstrate the superior performance of proposed CA-RQ over the standard RaptorQ code. In the meantime, extensive simulations have shown that our scheme not only offers much better subjective visual quality with less than 50% additional redundant symbols as compared to the Macroblock-Based UEP (MB-UEP) scheme, but also outperforms the MB-UEP and classical equal error protection (EEP)-based schemes, by a 0.45% $\sim$ 5.71% and 0.94% $\sim$ 6.78% margin, respectively, in reconstructed quality evaluated using the structural similarity (SSIM) index, across a reasonable range of redundancy proportions.

The Dispersion of Mismatched Joint Source-Channel Coding for Arbitrary Sources and Additive Channels

We consider a joint source channel coding (JSCC) problem in which we desire to transmit an arbitrary memoryless source over an arbitrary additive channel. We propose a mismatched coding architecture that consists of Gaussian codebooks for both the source reproduction sequences and channel codewords. The natural nearest neighbor encoder and decoder, however, need to be judiciously modified to obtain the highest communication rates at finite blocklength. In particular, we consider an unequal error protection scheme in which all sources are partitioned into disjoint power-type classes. We also regularize the nearest neighbor decoder so that an appropriate measure of the size of each power type class is taken into account in the decoding strategy. For such an architecture, we derive ensemble-tight second-order and moderate deviations results. Our first-order (optimal bandwidth expansion ratio) result generalizes the seminal results by Lapidoth (1996 and 1997). The dispersion of our JSCC scheme is a linear combination of the mismatched dispersions for the channel coding saddle-point problem by Scarlett, Tan, and Durisi (2017) and the rate-distortion saddle-point problem by the present authors, thus also generalizing these results.

Multi-Set Space-Time Shift Keying Assisted Adaptive Inter-Layer FEC for Wireless Video Streaming

he scalable video coding extension of H.265/High Efficiency Video Coding (HEVC) is capable of supporting diverse video resolutions. Due to the fact that the Enhancement Layer (EL) is encoded and decoded with the aid of the Base Layer (BL), the decodability of ELs is conditioned on that of the BL. Hence the EL frames occasionally have to be discarded as a result of corrupted BL frames. Therefore, potent Unequal Error Protection (UEP) schemes have been conceived for providing a stronger protection to the BL by invoking a lower coding rate based Forward Error Correction (FEC) or a higher transmit power for a specific Multiple-Input Multiple-Output (MIMO) sub-channel. This stronger protection is essential for the BL for the sake of both avoiding the waste of resources caused by the dropped undecodable EL bits and for improving the reconstructed video quality. In this treatise, we propose an adaptive system for transmitting the layered video bit stream over the wireless channel. The proposed system is capable of selecting an appropriate interlayer (IL) operation-aided FEC (IL-FEC) scheme in order to maintain the robustness of the system by comparing the near-instantaneous Signal-to-Noise Ratio (SNR) to pre-recorded reconfiguration thresholds. Our simulation results show that the proposed adaptive system is capable of providing better video quality over a large proportion of the channel Signal-to-Noise Ratio (SNR) range than its corresponding fixed-mode counterparts.

An Algorithm for Optimal Unequal Error Protection Rate Allocation Exploring Granular Channel Rates

In this letter an algorithm is proposed for optimal rate allocation constructed over a wide set of granular channel rates obtained from rateless codes to provide an ideal adjustment for an unequal error protection scheme. This algorithm is based on dynamic programming for resource allocations with capacity restrictions solved as a knapsack problem; formulated to find among each rate arrangement for a progressive bit stream the one that minimizes distortion and maximizes throughput, that represents the adaptation parameters to optimize the rate-distortion performance by balancing resources. Computational results have shown gains in distortion [peak signal-to-noise ratio (PSNR)] of approximately 20 dB over the maximum admissible SNR variation in comparison to the equivalent equal error protection rate. Enough protection levels have been defined to establish the best capacity convergence and algorithm efficiency.

Unequal Error Protection for Scalable Video Storage in the Cloud

Redundancy is necessary for a storage system to achieve reliability. Frequent errors in large-scale storage systems, for example, cloud, make it desirable to reduce the cost of recovery. Among all types of data in cloud storage, videos generally occupy significant amounts of space due to high volumes and the rapid development of video sharing and video-on-demand services. Unlike general data, videos can tolerate a certain level of quality degradation. This paper investigates multilayer video representations, such as scalable videos and simulcast streaming, and proposes an unequal error protection scheme based on local reconstruction codes (LRC) for video storage. By providing less protection for less important layers or video copies, a better tradeoff between storage and repair cost is achieved. Both theoretical and simulation results show that such a tradeoff can be achieved over the LRC with equal error protection, though the recovered video quality might be slightly lower in rare cases.

An unequal error protection scheme for non-binary LDPC using statistical QAM and prioritized mapping

Low Density Parity Check (LDPC) codes are among the most popular channel codes used nowadays because of their ability to achieve near channel capacity performances. However, with the ever-increasing demand for reliable transmission of data at higher data rates, there is a need to narrow down the gap between the performance of LDPC codes and the channel capacity. LDPC codes and Quadrature Amplitude Modulation (QAM) have been widely deployed in wireless communication standards such as the IEEE 802.11n and Digital Video Broadcasting-Second Generation Terrestrial (DVB-T2). Recently, several Unequal Error Protection (UEP) schemes have been used to enhance the performance of LDPC codes. In this paper an UEP scheme is proposed for Non- Binary LDPC codes with QAM. The scheme uses the statistical distribution of the source symbols to obtain a more efficient statistical QAM constellation. Additionally, it uses the degree distribution of the nodes of the LDPC codeword to achieve prioritized QAM mapping. Simulations revealed that the proposed scheme can provide Eb/N0 gains of up to 0.78 dB and 1.24 dB with 16-QAM and 64-QAM respectively in the range BER?10-2.

Cross‐layer source‐channel control for future wireless multimedia services: energy, latency, and quality investigation

Efficient use of available energy resources for real-time multimedia communication with a quality guarantee is one of the main challenges for future mobile computing systems. To meet the high quality-of-experience (QoE) demand of multimedia services, we propose a novel quality-driven joint source-channel coding (JSCC) scheme with an unequal error protection (UEP) technique that allocates bits by optimising source intra refreshing rates and channel correction coding rates. The key contribution of this work is that the frame importance diversity at the application layer is jointly considered with the error correction techniques and resource constraints at lower layers. For any given bit budget, the JSCC model is capable of allocating adaptive bits between source coding and channel coding among media streams. The source-aware UEP scheme is capable of dynamically allocating the error correction bits among frames, achieving the maximum overall QoE. Simulation results demonstrated that significant improvement in multimedia quality and remarkable energy/time conservation can be achieved by deploying the proposed group-based JSCC strategy, although the complexity is limited.