Equal Error Protection Scheme Research Articles

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.

Hierarchical Colour-Shift-Keying Aided Layered Video Streaming for the Visible Light Downlink

Colour-shift keying (CSK) constitutes an important modulation scheme conceived for the visible light communications (VLC). The signal constellation of CSK relies on three different-color light sources invoked for information transmission. The CSK constellation has been optimized for minimizing the bit error rate, but no effort has been invested in investigating the feasibility of CSK aided unequal error protection (UEP) schemes conceived for video sources. Hence, in this treatise, we conceive a hierarchical CSK (HCSK) modulation scheme based on the traditional CSK, which is capable of generating interdependent layers of signals having different error probability, which can be readily reconfigured by changing its parameters. Furthermore, we conceived an HCSK design example for transmitting scalable video sources with the aid of a recursive systematic convolutional (RSC) code. An optimization method is conceived for enhancing the UEP and for improving the quality of the received video. Our simulation results show that the proposed optimized-UEP 16-HCSK-RSC system outperforms the traditional equal error protection scheme by $\sim 1.7$ dB of optical SNR at a peak signal-to-noise ratio of 37 dB, while optical SNR savings of up to 6.5 dB are attained at a lower PSNR of 36 dB.

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.

Joint Source-Channel Rate Allocation in Parallel Channels

A fast rate-optimal rate allocation algorithm is proposed for parallel transmission of scalable images in multichannel systems. Scalable images are transmitted via fixed-length packets. The proposed algorithm selects a subchannel, as well as a channel code rate for each packet, based on the signal-to-noise ratios (SNRs) of the subchannels. The resulting scheme provides unequal error protection of source bits and significant gains are obtained over equal error protection schemes. An application of the proposed algorithm to JPEG2000 transmission shows the advantages of exploiting differences in SNRs between subchannels. Multiplexing of multiple sources is also considered, and additional gains are achieved by exploiting information diversity among the sources.

A novel approach to achieve unequal error protection for video transmission over 3G wireless networks

In this paper, we present a novel unequal error protection technique that enhances the video transmission quality over wireless networks. The case of application considered is a UMTS/TDD transmission system for H263 compressed and turbo-coded video sequences. The overall redundancy added to the compressed stream is non-uniformly distributed between the succeeding video frames in order to minimize the mean distortion over the transmitted sequence. The repartition of the redundancy on the video stream is optimized using an analytical approach which aims to alleviate the error propagation along the sequence. Different puncturing patterns of the rate 1 3 turbo-coder were considered in our simulations. The results obtained here are compared to those with a classical equal error protection scheme. We demonstrate that the gain in the system performances can reach 1.5 dB (in terms of the mean peak signal-to-noise ratio) without any significant increase in the transmission rate or the receiver complexity.

Serial unequal error-protection codes based on trellis-coded modulation

Unequal error-protection (UEP) codes that are designed using trellis-coded modulation (TCM) are proposed for use with a single data stream consisting of information with two levels of importance. To achieve UEP, the proposed scheme encodes the data according to the importance of the information by switching between two codes which use different signal constellations. Using simple trellis codes, it is shown that the error rate of the important information is lower than the error rate for an equivalent equal error-protection scheme.