High Throughput Iterative Decoders

High Throughput Iterative Decoders
Author: Engling Yeo
Publisher: Kluwer Academic Publishers
Total Pages: 250
Release: 2007-08-01
Genre: Computers
ISBN: 9781402076640

High Throughput Iterative Decoders: Towards Shannon Bound in VLSI addresses the algorithms and implementations of iterative decoders for error control in communication applications. The iterative codes are based on various concatenated schemes of convolutional codes, also known as turbo codes, and low density parity check (LDPC) codes. The decoding alogirthms are instances of message passing or belief propagation algorithms, which rely on the iterative cooperation between soft-decoding modules known as soft-input-Iterative decoding is a recent advacement in communication theory that is applicable to wireless, wireline, and optical communicatiosn systems. It promises significant advantage in bit-error rate (BER) performance at signal to noise ratios very close to the theoretical capacity bound. However, a direct mapping of the decoding algorithms leads to a multifold increase in the implementation complexity. As deep submicron technology matures, there is a possibility of implementing these applications that were once thought to be too complex to fit onto a single silicon die. We present the architectural and implementation issues related to the VLSI implementation of high throughput iterative decoders. The computational hardware and memory requirements of different competing architectures are discussed. This monograph also introduces reduced complexity modifications of algorithms that provide efficient mapping into architectures and VLSI implementations.

Semi-iterative Analogue Turbo Decoding

Semi-iterative Analogue Turbo Decoding
Author: Matthieu Arzel
Publisher:
Total Pages: 152
Release: 2006
Genre:
ISBN:

Over the past decade, telecommunication systems have dramatically grown providing services which require ever more data rate with ever more mobility. To sustain this growth, enhanced and new techniques were implemented in ever more optimised digital circuits. A novel approach could be soon necessary for some of these techniques, due to the limitations of their hardware implementations. Error correction is one of them. It allows to reduce the energy used to send information, but, when implemented on a chip, it is a bottleneck in terms of data throughput and of, paradoxically, power consumption. The analogue iterative decoding could solve this problem. This technique, promising high performance, requires new architectures and codes adapted to the constraints of analogue processing to challenge digital circuits in the field of industrial applications. A novel architecture and a novel turbo decoding algorithm, offering a good compromise between onchip area and data rate, are proposed in this thesis. They pave the way for integrating flexible high-speed analogue turbo decoders dealing with different frame lengths ranging from a few dozen to a few thousand bits. The new architecture and decoding algorithm are applied to a DVB-RCS-like code. The component 8-state decoder used in this new architecture was designed for a 0.25μm BiCMOS process. Dealing with frames made up of 24 double-binary symbols, it is, up to this date, one of the most complex analogue decoders ever designed. Implemented on chip, the circuit was successfully tested at 100Mbit/s while consuming 414mW on a 2.8V analogue core supply. It was shown to provide a bit error rate as close as 0.3dB to the digital one.