Convolutional Codes Search Based on Minimal Trellis Complexity

Bartolomeu Uchôa-Filho, Richard Demo Souza, Cecílio Pimentel, Mao-Chao Lin

DOI: 10.14209/sbrt.2005.680

Evento: XXII Simpósio Brasileiro de Telecomunicações (SBrT2005)

Keywords:

Abstract

This paper considers convolutional codes with low trellis complexity (i.e., low Viterbi decoding complexity) and good distance spectrum (i.e., good error performance). The trellis complexity of the convolutional code is defined as the total number of edge symbols per information bit in the minimal trellis module representing the code. We introduce a class of convolutional codes, called generalized punctured convolutional codes (GPCCs), which is broader than and encompasses the class of the standard punctured convolutional codes. A code in this class can be represented by a trellis module, the GPCC trellis module, whose topology resembles that of the minimal trellis module. The GPCC trellis module for a punctured convolutional code is shown to be isomorphic to the minimal trellis module. It is also shown by means of examples that this class contains codes with better distance spectrum than the best known punctured convolutional codes with the same code rate and trellis complexity. Good GPCCs obtained with the aid of a computer search are presented.

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