On the Performance of Turbo Codes in Quasi-Static Fading Channels

TL;DR

This paper develops an analytic method to evaluate turbo code performance in quasi-static fading channels, revealing that turbo codes only outperform convolutional codes when antenna diversity is used.

Contribution

It introduces a new analytic technique based on decoder convergence thresholds and compares turbo and convolutional codes under various conditions in fading channels.

Findings

Turbo codes and convolutional codes perform similarly without antenna diversity.

Turbo codes outperform convolutional codes only with antenna diversity.

Performance is independent of interleaver size and code parameters in quasi-static fading.

Abstract

In this paper, we investigate in detail the performance of turbo codes in quasi-static fading channels both with and without antenna diversity. First, we develop a simple and accurate analytic technique to evaluate the performance of turbo codes in quasi-static fading channels. The proposed analytic technique relates the frame error rate of a turbo code to the iterative decoder convergence threshold, rather than to the turbo code distance spectrum. Subsequently, we compare the performance of various turbo codes in quasi-static fading channels. We show that, in contrast to the situation in the AWGN channel, turbo codes with different interleaver sizes or turbo codes based on RSC codes with different constraint lengths and generator polynomials exhibit identical performance. Moreover, we also compare the performance of turbo codes and convolutional codes in quasi-static fading channels under the condition of identical decoding complexity. In particular, we show that turbo codes do not outperform convolutional codes in quasi-static fading channels with no antenna diversity; and that turbo codes only outperform convolutional codes in quasi-static fading channels with antenna diversity.