Analysis and modeling of optimal error protection for embedded codestreams

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 view of increasing use of video transmission over wireless channels, a lot of research efforts have been made to trade-off the error resiliency and transmission bandwidth requirements. This in turn has led to development of various unequal error protection (UEP) schemes. In this paper, the performance of optimized 2-layered and 3-layered UEP schemes using hierarchical 64 QAM (64-HQAM) for wavelet-transformed images coded with set partitioning in hierarchical trees (SPIHT) algorithm and transmitted over additive white Gaussian noise (AWGN) channel is investigated. A look-up table (LUT) based approach to select the optimal values of modulation parameters of 64-HQAM for different channel conditions is suggested so as to reduce the computational complexity. Simulation results show that 3-layered optimized 64-HQAM-based UEP outperforms corresponding non-optimized UEP. Also, 3-layered optimized UEP scheme using 64-HQAM performs slightly better as compared to optimized 2-layered UEP scheme using 64-HQAM.

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.

In this paper we propose an image coding scheme based on Block Turbo Codes (BTC) for protecting SPIHT coded images transmitted over wireless channels. An Unequal Error Protection (UEP) scheme using different product codes is also presented. The optimization of the UEP scheme under a transmission budget constraint is investigated. Performance of the proposed system are first evaluated over Gilbert-Elliott (GE) channels. They are then compared to the well-known system of Sherwood and Zeger, through numerical simulations over a single path Rayleigh fading channel. Then, we present an optimized mobile image transmission framework involving a multiuser asynchronous DS-CDMA transmission system over Rayleigh multipath channels. Simulation results for the 512x512 Lena image, transmitted over the ITU Vehicular A channel, show that a significant gain in PSNR is obtained by using the SIC/RAKE multiuser detector in comparison with a conventional detection by the RAKE receiver. Furthermore, performance are also improved when introducing the UEP scheme.

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.

The utilization of forward error correction (FEC) schemes for stereo video streaming is investigated. Stereo video is categorized in 3 layers and each layer is protected with different protection ratios for efficient streaming. Systematic Reed-Solomon (RS) and Luby Transform (LT) codes are utilized as the error protection schemes. Detailed simulations are performed in order to observe the optimum unequal error protection (UEP) strategies for the defined video layers. Moreover, as a result of these simulations the performance comparison of RS and LT codes for video streaming is provided.

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.

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.

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.

An error protection scheme for a vector-quantization (VQ)-based code excited linear predictive (CELP) coder for mobile radio applications is proposed. To arrive at an appropriate error protection strategy, the sensitivity of the different parameters in the CELP coder are studied, and then unequal error protection is designed according to parameter sensitivities. Different levels of error protection are provided by the use of punctured convolutional codes. The mobile radio channel is modeled as a Rayleigh fading channel. A convolutional interleaving technique is used to combat fading. The combined source and channel codec for this application has a total bit rate of 6.4 kb/s, of which 1.6 kb/s is used for channel coding. Simulation result show that the resulting codec can provide good quality speech at a Doppler frequency of 48 Hz and a channel bit error rate as high as 10/sup -2/. >

Traditional unequal error protection (UEP) schemes have some limitations and problems, such as the poor UEP performance of high priority data and the seriously sacrifice of low priority data in decoding property. Based on the reasonable applications of different degree distributions in LT codes, this paper puts forward a novel UEP LT coding scheme with a simple feedback to compile these data packets separately. Simulation results show that the proposed scheme can effectively protect high priority data, and improve the transmission efficiency of low priority data from 2.9% to 22.3%. Furthermore, it is fairly suitable to apply this novel scheme to multicast and broadcast environments since only a simple feedback introduced.

Asymmetric Digital Subscriber Line (ADSL) is a broadband communications technology which is widely used for transmitting high bandwidth data such as audio and video over the internet. However, ensuring a good Quality of Service (QoS) in the transmission of such data over ADSL is challenging due to channel impairments such as noise and crosstalk. Moreover, given that the total monthly fixed data traffic is increasing at a phenomenal rate, (QoS) management is becoming a crucial issue. This paper proposes an enhanced transmission scheme for audio over ADSL. The proposed scheme exploits the unequal importance of the subbands generated by an MP1 codec to offer varying protection to them during ADSL transmission. This is achieved by multiplexing the bit streams from the subbands before Discrete Multi-tone Modulation (DMT) so that bit streams corresponding to more important subbands are offered higher protection than the least important ones. Additionally, a sophisticated retransmission protocol is proposed which allows frames from more important subbands to benefit from a greater number of retransmissions than least important ones. The retransmission protocol uses eight different Negative Acknowledgement (NACK) packet types which allow adaptive multiplexing of frames at the transmitter. The proposed Unequal Error Protection (UEP) scheme provides an average gain of over 28 dB in Segmented Signal to Noise Ratio (SSNR) over a conventional Equal Error Protection (EEP) one but incurs a negligible loss in throughput.

In this work, we propose a stereoscopic video streaming system that uses rateless codes (Raptor codes) as the error protection scheme. Initially, we model the rate-distortion (RD) curve of video encoder and performance of channel codec. Then, we estimated the distortion on the stereoscopic video quality caused by packet losses. Finally, analytical models and estimated single packet loss distortions are used to minimize the end-to-end distortion and obtain optimal encoder bit rates and unequal error protection (UEP) rates. The simulation results clearly demonstrates the significant quality gain against the non-optimized schemes.

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.

Multimedia delivery over Wireless Sensor Networks (WSNs) is energy critical. In this paper, we study an energy constrained cross layer optimization scheme to improve digital image quality in cross polarization discrimination (XPD) based Multiple Input Multiple Output (MIMO) WSNs. The contribution of this research can be summarized in three parts. First, link layer energy consumption and packet loss ratio in multirate XPD based MIMO WSN are modeled. Secondly, XPD based modulation optimization cross link and physical layer is proposed, achieving considerable energy efficiency. Finally, a new Position-Value (P- V) based Unequal Error Protection (UEP) scheme is studied and discussed in XPD MIMO WSNs, with more efficient resource allocation compared to traditional approaches. Simulation results show the proposed modulation optimization scheme improves energy efficiency considerably, and position based UEP achieves significant distortion-energy gain compared with traditional layer based resource allocation schemes in XPD MIMO WSNs.