Instead of a random interleaver, an algebraic interleaver interconnecting two simple convolutional codes with feedback encoders forms an algebraic quasi-cyclic code. An (nC , k) convolutional code in tailbiting form becomes a quasi-cyclic (QC) linear code of length LnC for some L = Mn. Interleavers with a period M connect two such codes to produce a QC turbo code. The QC turbo codes check equat...

Turbo decoding is based on the concept of maximum likelihood decision on blocks of data. The decision on a bit affects the decoding of subsequent bits. Fading is a type of corruption whose effect can be extended over a period of multiple bits, resulting in significant performance degradation for turbo code. In this paper, a Markov process is utilized to model a fading channel, and bit error rat...

In this study, turbo codes were investigated in a slow frequency-hopped binary frequency shift keying spread spectrum (FH/BFSK-SS) system with partial band jamming and full-band thermal noise. A soft decision decoding metric which includes automatic gain control (AGC) is proposed for turbo code decoding with a non-coherent square law receiver of FH/BFSK. The study focused on the performance com...

—This letter is concerned with a family of modified turbo-type codes, referred to as turbo-SPC (single parity check) codes. A technique based on the SPC code is introduced to replace puncturing for rate adjustment. A noticeable feature of the proposed scheme is the significantly reduced decoding complexity compared with the standard punctured turbo code. The cost reduction factor becomes more n...

Despite the considerable research effort towards the analysis and understanding of the nature of turbo decoding, a clear identification of the underlying optimization problem the turbo decoder attempts to solve is still missing. In this paper, we link the turbo decoding algorithm to maximum likelihood (ML) sequence detection by demonstrating how the turbo decoder can be systematically derived s...

We study the use of turbo-coded modulation for wireless communication systems with multiple transmit and receive antennas over block Rayleigh fading channels. We describe an effective way of applying turbo-coded modulation as an alternative to the current space–time codes with appropriate interleaving. We study the performance with the standard iterative turbo decoding algorithm, as well as the...

In a recent paper, it is shown that if Pearl's belief propagation algorithm is applied to the Bayesian belief network of a turbo code, the turbo decoding algorithm immediately results. From this perspective, it is recognized that the turbo coding structure imposes unnecessary diierentiation on the parity checks and the turbo decoding algorithm speciies a seemingly arbitrary sequential activatio...

Recent studies have shown that Space-Time code is an effective approach to increasing the data rate over wireless channels. Turbo-based Space-Time codes take advantage of both the diversity techniques of Space-Time systems and the randomness of the Turbo codes. In this paper, we compare two Turbo-based Space-Time Codes and their approximate versions with respect to energy consumption and perfor...

We present an approach to design of fault tolerant computing systems. In this paper, a technique is employed that enable the combination of several codes, in order to obtain flexibility in the design of error correcting codes. Code combining techniques are very effective, which one of these codes are turbo codes. The Algorithm-based fault tolerance techniques that to detect errors rely on the c...

Turbo code is a great achievement in the field of communication system. It can be created by connecting a turbo encoder and a decoder serially. A Turbo encoder is build with parallel concatenation of two simple convolutional codes. By varying the number of memory element (encoder configuration), code rate (1/2 or 1/3), block size of data and iteration, we can achieve better BER performance. Tur...