FPGA design and implementation of systolic array-based viterbi decoders

The Viterbi algorithm is known to provide an efficient method for the maximum likelihood decoding of convolutional codes. In this thesis, a design and FPGA implementation of a Viterbi decoder with a constraint length of 9 and code rate of 1/2 is presented. In this design, a novel systolic array architecture with time multiplexing, arithmetic pipelining and clock-to-data skews tolerance is developed. Further, by modifying this Viterbi algorithm, an adaptive Viterbi algorithm that is based on strongly-connected trellis decoding is proposed. Using the proposed adaptive algorithm, a design and FPGA implementation of a low-power adaptive Viterbi decoder with a constraint length of 9 and code rate of 1/2 is presented. The systolic array-based architecture used in this adaptive Viterbi decoder is a modified version of the architecture used for the non-adaptive Viterbi decoder in that the latter is modified to include the modules, which are needed for generating the survivor information and for eliminating the spurious toggles in the adaptive Viterbi decoding process

VLSI Architectures for WIMAX Channel Decoders

This chapter describes the main architectures proposed in the literature to implement the channel decoders required by the WiMax standard, namely convolutional codes, turbo codes (both block and convolutional) and LDPC. Then it shows a complete design of a convolutional turbo code encoder/decoder system for WiMax.Comment: To appear in the book "WIMAX, New Developments", M. Upena, D. Dalal, Y. Kosta (Ed.), ISBN978-953-7619-53-

TCM Decoding Using Neural Networks

This paper presents a neural decoder for trellis coded modulation (TCM) schemes. Decoding is performed with Radial Basis Function Networks and Multi-Layer Perceptrons. The neural decoder effectively implements an adaptive Viterbi algorithm for TCM which learns communication channel imperfections. The implementation and performance of the neural decoder for trellis encoded 16-QAM with amplitude imbalance are analyzed

Reconfigurable Turbo/Viterbi Channel Decoder in the Coarse-Grained Montium Architecture

Mobile wireless communication systems become multi-mode systems. These future mobile systems employ multiple wireless communication standards, which are different by means of algorithms that are used to implement the baseband processing and the channel decoding. Efficient implementation of multiple wireless standards in mobile terminals requires energy-efficient and flexible hardware. We propose to implement both the baseband processing and channel decoding in a heterogeneous reconfigurable system-on-chip. The system-on-chip contains many processing elements of different granularities, which includes our coarse-grained reconfigurable MONTIUM architecture. We already showed the feasibility to implement the baseband processing of OFDM and WCDMA based communication systems in the MONTIUM. In this paper we implemented two kinds of channel decoders in the same MONTIUM architecture: Viterbi and Turbo decoding

A survey of the state-of-the-art and focused research in range systems

In this one-year renewal of NASA Contract No. 2-304, basic research, development, and implementation in the areas of modern estimation algorithms and digital communication systems have been performed. In the first area, basic study on the conversion of general classes of practical signal processing algorithms into systolic array algorithms is considered, producing four publications. Also studied were the finite word length effects and convergence rates of lattice algorithms, producing two publications. In the second area of study, the use of efficient importance sampling simulation technique for the evaluation of digital communication system performances were studied, producing two publications

Trellis coded modulation techniques

The subject of this thesis is an investigation of various trellis coded modulation (TCM) techniques that have potential for out-performing conventional methods. The primary advantage of TCM over modulation schemes employing traditional error-correction coding is the ability to achieve increased power efficiency without the normal expansion of bandwidth introduced by the coding process. Thus, channels that are power limited and bandwidth limited are an ideal application for TCM. In this thesis, four areas of interest are investigated. These include: signal constellation design, multilevel convolutional coding, adaptive TCM and finally low-complexity implementation of TCM. An investigation of the effect of signal constellation design on probability of error has led to the optimisation of constellation angles for a given channel signal to noise ratio and a given code. The use of multilevel convolutional codes based on rings of integers and multi-dimensional modulation is presented. The potential benefits of incorporating several modulation schemes with adaptive TCM which require a single decoder are also investigated. The final area of investigation has been the development of an algorithm for decoding of convolutional codes with a low complexity decoder. The research described in this thesis investigated the use of trellis coded modulation to develop various techniques applicable to digital data transmission systems. Throughout this work, emphasis has been placed on enhancing the performance or complexity of conventional communication systems by simple modifications to the existing structures