Unveiling turbo codes: some results on parallel concatenated coding schemes
IEEE Transactions on Information Theory
A distance spectrum interpretation of turbo codes
IEEE Transactions on Information Theory - Part 1
A logarithmic upper bound on the minimum distance of turbo codes
IEEE Transactions on Information Theory
IEEE Journal on Selected Areas in Communications
| Hi-index | 0.00 |
Turbo Codes are a class of powerful error correction codes that were introduced in 1993 by a group of researchers from France, which has the performance near the limit of Claude Shannon. After the introduction of turbo codes it has given raise a tremendous research work related to the new coding theory. This paper addresses the performance of Turbo codes by examining the codes' distance spectrum. It is well known that error floor occurs in the performance curve of turbo codes at moderate to high signal-to-noise ratio. The cause of error floor is due to the relatively low free distance of the codewords. Several techniques were proposed by researchers to lower the error floor. These techniques are assessed in this paper. To determine the free distance several algorithms were developed by different researchers. In this paper we used one of the recent algorithm to evaluate the distance spectrum of Turbo codes. We concentrate our analysis to measure and explain the distance spectrum of UMTS (Universal Mobile Telecommunication System), cdma2000 and CCSDS (Consultative Committee for Space Data Systems) standards Turbo Codes. It is shown that the distance spectrum depends on the code rate, interleaver size and the interleaver type. This distance spectrum of turbo codes can be used to estimate its performance at medium to higher SNR (signal to noise ratio). From our analysis we find out that the distance spectrum is one of the elementary issues using which one can find the optimum architecture of Turbo codes for specific application.