Hybrid Joint Source Channel Decoding for Progressive JPEG Image Transmission

In this paper, we combine two Joint Source Channel Decoding (JSCD) approaches and apply them to progressive JPEG image transmission. The first JSCD approach consists of optimizing the allocation of the channel code-rates to the different layers of the JPEG image, and is commonly referred as Unequal Error Protection (UEP). The second JSCD strategy exploits a priori probabilities obtained from source statistics as well as the residual redundancy of the source to improve channel decoding. Additionally, we propose an error resilient sub-categorization scheme for the DC layer so as to reduce the effect of the channel-induced distortion. The hybrid JSCD scheme is implemented with Rate Compatible Punctured Turbo Codes and also with the bandwidth efficient Rate Compatible Punctured Turbo Trellis Coded Modulation. Gains of over 10 dB in PSNR are obtained with the hybrid JSCD scheme as compared to a conventional JPEG image transmission scheme.     

Robust JPEG image transmission using unequal error protection and code combining

JPEG image transmission over noisy channels is highly problematic due to the sensitivity of the JPEG bit stream to error propagation. The use of resynchronization markers and channel coding do not alleviate the problem completely thus making retransmissions inevitable. In packetized image transmission, image packets are repeated n times, to ensure reliable transmission. This paper proposes a new unequal error protection (UEP) scheme which jointly optimizes the allocation of channel code rates and number of repeats to image packets, subject to a constraint on the maximum overall transmission rate. The coding scheme used is the rate compatible punctured convolutional code coupled with the code‐combining technique. An unequal allocation of headers to the image packets is also performed in order to reduce the overall distortion due to error propagation. Simulation results show that the proposed UEP scheme provides a gain of more than 8 dB in peak‐to‐peak signal‐to‐noise ratio over a tandem scheme. The flexibility of the proposed scheme, and the major performance gains obtained, make the scheme appealing for applications like, web‐based image browsing, multi‐hop networks, and wireless image transmission. Copyright © 2007 John Wiley & Sons, Ltd.     

On the Logical Computational Complexity Analysis of Turbo Decoding Algorithms for the LTE Standards

Evaluating the computational complexity of decoders is a very important aspect in the area of Error Control Coding. However, most evaluations have been performed based on hardware implementations. In this paper, different decoding algorithms for binary Turbo codes which are used in LTE standards are investigated. Based on the different mathematical operations in the diverse equations, the computational complexity is derived in terms of the number of binary logical operations. This work is important since it demonstrates the computational complexity breakdown at the binary logic level as it is not always evident to have access to hardware implementations for research purposes. Also, in contrast to comparing different Mathematical operations, comparing binary logic operations provides a standard pedestal in view to achieve a fair comparative analysis for computational complexity. The usage of the decoding method with fewer number of binary logical operations significantly reduces the computational complexity which in turn leads to a more energy efficient/power saving implementation. Results demonstrate the variation in computational complexities when using different algorithms for Turbo decoding as well as with the incorporation of Sign Difference Ratio (SDR) and Regression-based extrinsic information scaling and stopping mechanisms. When considering the conventional decoding mechanisms and streams of 16 bits in length, Method 3 uses 0.0065% more operations in total as compared to Method 1. Furthermore, Method 2 uses only 0.0035% of the total logical complexity required with Method 1. These computational complexity analysis at the binary logical level can be further used with other error correcting codes adopted in different communication standards.

     

Wireless JPEG Image Transmission Using Multiple Diversity Combining and Unequal Error Protection

In this paper we investigate the performance of JPEG image transmission over the IEEE 802.11a WLAN, using Multiple Diversity Combining (MDC) and Unequal Error Protection (UEP). An MDC scheme is obtained by simultaneously employing transmitter diversity, receiver diversity and retransmission diversity. UEP is performed by first optimizing the number of headers allocated to the subbands of a JPEG image to prevent error propagation, and secondly by optimizing the number of retransmissions with a view to minimize the channel induced distortion. The MDC-UEP strategy has been employed with both Convolutional and Turbo codes. Simulation results show that a gain of 8 dB in PSNR can be obtained with MDC-UEP in the range 0 dB ≤ Eb/No ≤ 3 dB, over a scheme which uses MDC with Equal Error Protection (EEP). Moreover MDC-UEP with Turbo codes provides a gain of 0.5 dB in PSNR and 5 percent in throughput over an MDC-UEP scheme with Convolutional codes.     

Enhancing the Error Performance of 5G New Radio Using Hierarchical and Statistical QAM

Wireless Personal Communications - The latest mobile network technology, 5G New Radio (NR), utilizes the combination of Low-Density Parity Check (LDPC) codes, which are powerful forward error...     

Highly scalable JPEG image transmission with unequal error protection and optimal feedback

This paper investigates the performance of three different Unequal Error Protection (UEP) schemes for progressive JPEG image transmission using delay-constrained hybrid ARQ, with iterative bit and symbol combining. The first UEP scheme considers only the optimization of channel code-rates and keeps the number of retransmissions fixed for all the subbands of the image. The second one optimizes both the channel code-rates and retransmissions, while the third only considers the optimal allocation of retransmission requests. The UEP schemes are designed with two different coding techniques. The first one employs Rate Compatible Punctured Turbo Codes (RCPT) with iterative bit combining and, is suitable for applications requiring high power efficiency. For the second one we propose a new coding strategy, Rate Compatible Punctured Turbo Trellis Coded Modulation (RCPTTCM) with iterative symbol combining, which provides high scalability and bandwidth efficiency. Gains of over 9 dB in Peak-Signal-to-Noise-Ratio are obtained with the UEP schemes as compared to their corresponding Equal Error Protection (EEP) schemes.     

Performance of joint source–channel decoding with iterative bit combining and detection

A joint source–channel decoding scheme (JSCD) with iterative bit combining (IBC) is proposed, which exploits two types of a priori information. The first one is the a priori bit probabilities obtained from source statistics, and the second is the channel a priori probabilities obtained from saved extrinsic information of previous transmissions. The JSCD-IBC scheme also incorporates iterative detection as both a stopping criteria and mechanism for triggering retransmissions. This adds an implicit adaptivity to the system and prevents excess iterations/retransmissions from being effected. The performance of the JSCD-IBC scheme is evaluated with four different iterative detection schemes and also two different types of variable length codes, Huffman and reversible variable length codes. Simulation results show that a significant performance gain in terms of bit error rate, throughput, and number of iterations can be achieved with the JSCD-IBC scheme as compared to a separate decoding scheme.