Unequal error protection applied to JPEG image transmission using turbo codes

The MPEG-4 video compression standard incorporates several techniques to create error-resilient coded video. These techniques are effective against a certain level of errors. However, wireless channels often have very high error rates; thus channel coding is needed to reduce the number of errors in the compressed bitstream that is sent to the MPEG-4 video decoder. The structure of an MPEG-4 compressed bitstream lends itself to using unequal error protection to ensure fewer errors in the important portions of the bitstream. This paper discuses how unequal error protection can be used with the MPEG-4 error resilience tools and describes several experiments using both unequal and equal error protection on video sent through a simulated GSM channel. The results of these experiments show that when the bit error rate is high, unequal error protection can improve reconstructed video quality by as much as 1 dB compared with equal error protection.

Give a limited bandwidth, unequal error protection (UEP) via channel coding with different code rates for different important regions of bitstream may yield much less error contamination than equal error protection (EEP). We propose an optimal code rate allocation scheme that minimizes error contamination after channel and source decoding. We use JPEG2000 for source coding and turbo product code (TPC) for channel coding as an example to demonstrate this technique with ultraspectral sounder data. The statistics of erroneous pixels after TPC and JPEG2000 decoding are used to determine the optimal channel code rates for each wavelet resolution. The proposed UEP scheme significantly reduces error contamination when compared to its EEP counterpart. The optimal code rate allocation needs to be determined only once, given any predefined set of available channel codes, desired code rate, and noise level.

A technique to improve the rendering quality of novel views for colour plus depth based 3D video is proposed. Most depth discontinuities occur around the edges of depth map objects. If information around edges of both colour and depth map images is lost during transmission, this will affect the quality of the rendered views. Therefore this work proposes a technique to categorize edge and surrounding areas into two different regions (Region Of Interests (ROIs)) and later protect them separately to provide Unequal Error Protection (UEP) during transmission. In this way the most important edge areas (vital for novel view rendering) will be more protected than other surrounding areas. This method is tested over a H.264/AVC based simulcast encoding and transmission setup. The results show improved rendered quality with the proposed ROI-based UEP method compared to Equal Error Protection (EEP) method.

Scalable video coding technique has been desired for many years to fulfill the requirement of reliable transmission of video over heterogeneous networks. It allows for simple solutions in adaptation to network constraint and user capabilities by providing a full scalability including temporal, spatial and quality scalability. Various coding structures will dramatically affect the overall performance of the system. In this paper, we develop a new joint source and channel coding scheme for wireless broadcasting making use of H.264/SVC considering the various clients' statistics such as the accessing bandwidth and the error rate. First, an effective algorithm is carried out to distribute proper amount of source codes and channel codes to the base layer to guarantee that all the clients can receive the video with a minimum quality. Second, to deal with the burst packet loss, we propose to apply the unequal error protection (UEP) scheme on the enhancement layers using the interleaved packetization to make sure that all the lower layers can be decoded if an enhancement layer is correctly received. To maximize the system-defined utility function, fast algorithms are designed to dynamically allocate the source coding rate and the channel coding rate for the scalable bit-stream given the clients' distribution. Experiments are conducted to verify the performance of the proposed algorithm against the other two schemes, where equal error protection (EEP) and UEP schemes with different coding structures are employed. The results demonstrate the superiority of the proposed scheme and the improvement is up to 2 dB.

In this paper we propose a new image transmission scheme for an image which has been compressed using wavelet image compression and coded with a Variable Length Code. The proposed scheme applies Unequal Error Protection (UEP) at three different stages, namely the source coding, channel coding and retransmission stage. UEP at the source coding stage is employed to unequally protect the image subbands against error propagation, which arises due to variable length coding. At the channel coding stage, UEP is applied by the use of Rate Compatible Punctured Convolutional codes to unequally allocate coding redundancy to the image subbands. Finally at the retransmission stage, UEP is applied by assigning different synchronization error tolerances to the image subbands. Gains of over 4 dB in terms of Peak to Peak Signal to Noise Ratio (PSNR) is achieved by employing the integrated UEP scheme as compared to a standard Equal Error Protection Scheme.

This paper presents a coding scheme to improve the performance of three-dimensional (3D) audio. The scheme is designed by the idea of joint source channel coding (JSCC) and is implemented by Expanding Window Fountain (EWF) codes for the 3D audio bitstreams after source coding of spatial squeeze surround audio coding (S3AC). EWF is one of unequal error protection (UEP) LT codes and the proposed scheme is achieved by that method for the case of two levels. Different from other transmissions with equal error protection (EEP) for each part of bitstreams, when transmitting the two parts of the bitstreams with downmixed mono signals and spatial side information after S3AC coding, this approach provides more protection to the part of spatial side information and comparatively less protection to the downmixed mono signals, and results in the improvement of the performance of the reproduced 3D audio especially on the aspect of the spatial perception. Objective simulation experiment has shown the proposed UEP scheme achieves a better performance than the EEP scheme on the aspect of spatial perception, for the bits error rates (BER) of spatial parameters can decrease dramatically to a low value of about 10−4, but BERs of downmixed mono signals and the case of EEP just decrease slightly to about 10−3.

We present a dynamic unequal error protection (UEP) framework for the embedded image bit streams over noisy channels. A general source model for M-rate UEP schemes is derived and an optimization algorithm for 2-rate dynamic UEP schemes is developed. To facilitate the design and implementation of UEP schemes, we also derived a necessary condition and an upper bound for UEP gains. Simulation results demonstrate about 0.3 dB improvements over equal error protection (EEP) schemes at the price of negligible overheads while the progressiveness of the original bit streams is still kept.

In wireless relay networks (WRNs), multiple source nodes communicate with a single destination node through a common relay network. Different source nodes may have different error protection or recovery time requirements. In this paper, we focus on unequal error protection (UEP) distributed network coding (DNC) design for WRNs. Specifically, we propose a continuous UEP method based on fountain codes with the objective of satisfying the UEP or unequal recovery time (URT) requirements. Then based upon this UEP method, we develop an adaptive UEP DNC scheme to realize adaptive UEP in WRNs. We analyze the properties of the proposed adaptive UEP DNC scheme and derive the upper and lower bit error rate (BER) bounds for it over Rayleigh fading channels under maximum-likelihood (ML) decoding. Simulation results show that the proposed adaptive UEP DNC scheme has desirable UEP and URT properties. The transmitted data from the source nodes in different protection groups can be recovered successfully under their performance requirements in a shorter time by using the adaptive UEP DNC scheme.

In this paper, we propose a novel algorithm for constructing an Unequal Error Protection (UEP) FEC code targeted towards video streaming applications. A concatenation of a set of parallel outer block codes followed by a packet interleaver and an inner block code is presented. The algorithm calculates on the fly the optimal allocation of the code rates of the inner and outer codes. When applied to video streaming applications using H.264, the discussed UEP framework achieves gains of up to 5dB in video quality compared to equal error protection (EEP) FEC at the same code rate.

In this paper, a power water-filling scheme for unequal error protection (UEP) based on set partitioning in hierarchical trees (SPIHT) coded image transmission over multiple input multiple output(MIMO) channels is proposed. SPIHT coded image information is divided into different sub-streams according to their different importance, which is allocated to different channels. Then unequal error protection (UEP) of image with singular value decomposition and power water-filling policy is achieved. The simulation results show that the quality of reconstructed image of using UEP is better than equal error protection (EEP).

Video streaming over wireless channel encounters many challenges due to the time-varying characteristics of wireless channels and limited network bandwidth. In this paper, we investigate an adaptive forward error correction (FEC) scheme for streaming the stored MPEG-4 FGS bit-stream from the video server to the clients over wireless channel. In this scheme, the base layer is transmitted reliably and the enhancement layer is protected with unequal error protection (UEP) scheme. Taking the fine-grained characteristics of FGS into account, we propose a decodable rate maximized criterion to optimally allocate the bit rate between the source rate and the channel coding rate and dynamically adapt to the varying network condition. Experimental results show that Compared with fixed unequal error protection (UEP) and equal error protection (EEP), our proposed method can provide a better performance.

An improved MIMO system implementing joint source and channel coding in the form of Rate Compatible Punctured Convolutional Code (RCPC Code) and Unequal Error Protection (UEP) is proposed. To ensure a multiplexing gain, a layered architecture, V-BLAST, is employed. Analytical BER is presented and numerical simulations are done to analyze the system performance. The proposed coding scheme allows for consistently higher error-protection level as the code rate decreases. It is also shown that whilst the lower code rates outperforms the higher ones, in terms of larger free distance and lower BER, the SNR range covered is narrower at decreasing levels of BER. This implies the potential bandwidth efficiency to be gained if the higher code rates are used for lower-priority data bits.

On account of the wireless channel interference, transmission data tends to be erroneously decoded at the receiver. Even received with errors in some extent, the video can still be successfully recovered because of its error resilience, e.g. videos encoded with H.264/AVC. According to recent research, when a bit sequence is modulated to constellation symbols, different bit positions of symbols may have different probabilities of error occurrence. To exploit whether differential protection could be provided to different data bits of a video streaming based on this feature, our experiment implements this UEP (unequal error protection) scheme together with the data partitioning mechanism in H.264/AVC video encoding standards. The experiment results show the UEP scheme gains 5 dB of PSNR improvement in average than the EEP (equal error protection) scheme. While once massive errors occur, packets must be discarded and retransmissions are required, so additional resource consumption is unavoidable. To solve this problem, unequal loss protection (ULP) for H.264 bit stream is proposed in this paper. And we find a fact through experiments that when bandwidth resource is limited, insignificant partial data of H.264 bit stream could be discarded selectively without arousing obvious video quality degradation. Our simulation shows that when the unimportant network abstraction layer units (NALU) of H.264 bit stream are discarded, approximately 20 % of bandwidth resource is saved.

Two-fold turbo codes have recently been introduced as the least complex member of the multifold turbo code family, and they have been shown to outperform their conventional symmetric and asymmetric cousins in the waterfall region. The article introduces a simple method that allows two-fold turbo codes to offer bilevel unequal error protection. Also, the application of the unequal error protection to a still image coding technique, i.e. hue-saturation-luminance coding, is explained and the pixel error performance results under Gaussian conditions are presented. According to the simulation results, the proposed scheme outperforms its conventional counterpart by up to 0.7 dB. Furthermore, with the new unequal error protection coding scheme, under certain channel conditions, significant savings in decoder iterations are achieved, without compromising the received image quality. Although the unequal error protection is limited to bilevel within the scope of this article, the same technique can be used to provide multilevel error protection.

Using the scalable video coding (SVC) extension of the H.264/AVC video coding standard, encoding a video sequence yields a quality, resolution, and frame-rate scalable bit-stream. This means that a version of the video sequence with a lower resolution, quality and/or frame rate can be obtained by extracting selected parts of the scalable bit-stream, without the need for re-encoding. In this way, easy adaptation of the video material to the end-users' device (computational power and display resolution) and channel characteristics is possible. In this paper, the use of unequal error protection (UEP) for error-resilient transmission of H.264/SVC-encoded video sequences is studied. By using unequal error protection, graceful degradation of the video quality is achieved when the targeted packet loss probability is exceeded. In contrast, using equal error protection (EEP), an immediate and dramatic drop in quality is observed under these conditions.