Iterative decoding of a serial concatenated coding scheme consisting of an outer convolutional code and M -ary orthogonal Walsh modulation as inner Walsh-Hadamard block code in an OFDM-CDMA system is applied. New aspects arise because OFDM enables the iterative decoding structure to exploit time as well as frequency diversity of a mobile channel. Moreover, the paper points out the low complex s...

This paper presents an iterative decoding method in the coded MFSK (multilevel frequency shift keying)/FH-SSMA (frequency hopping-spread spectrum multiple access) system. The kernel of the system, which is a symbol APP (a posteriori probability) calculator, accepts channel values and a priori information from the channel decoder and generates reliability values of the received symbols. The chan...

Abstract – In this paper, which is the first part in a series of three, a formal theory and construction methods for low-density convolutional (LDC) codes (including turbo-codes) are presented. The principles of iterative decoding of LDC codes are formulated, and an iterative algorithm for decoding of homogeneous LDC codes is described. Some simulation results are also presented. In the followi...

Transmission of convolutionally encoded multiple descriptions over noisy channels can benefit from the use of iterative source-channel decoding. The authors first modified the BCJR algorithm in a way that symbol a posteriori probabilities can be derived and used as extrinsic information to improve the iterative decoding between the source and channel decoders. The authors also formulate a recur...

In this study, we propose two hybrids concatenated Super-Orthogonal Space-Time Trellis Codes (SOSTTC) applying iterative decoding in Orthogonal Frequency Division Multiplexing (OFDM) over frequency selective fading channels. The coding scheme is based on the concatenation of convolution coding, interleaving and space-time coding along multiple-transmitter/multiple-receiver diversity systems. Th...

A suboptimal iterative demodulation and decoding receiver is presented for an LDPC coded spatial multiplexing OFDMA system. The proposed receiver is based on spatial demultiplexing at the first iteration and the interference cancellation with soft decoding outputs at the following iterations. It is shown that the proposed receiver can reduce the complexity of the optimal iterative demodulation ...

In this paper we introduce the iterative decoding principle, “the turbo principle”, for the bidimensional Turbo Product Codes (TPC’s). The constituent codes used for encoding on rows and columns are two concatenated (7,4) Hamming block codes. Several Soft Input Soft Output (SISO) algorithms can be used for the iterative decoding process. At each iteration, the two decoders decode all rows, then...

Iterative algorithms are an attractive approach to approximating optimal, but high-complexity, joint channel estimation and decoding receivers for communication systems. We present a unified approach based on factor graphs for deriving iterative message-passing receiver algorithms for channel estimation and decoding. For many common channels, it is easy to find simple graphical models that lead...

In this study, we propose two hybrids concatenated Super-Orthogonal Space-Time Trellis Codes (SOSTTC) applying iterative decoding in Orthogonal Frequency Division Multiplexing (OFDM) over frequency selective fading channels. The coding scheme is based on the concatenation of convolution coding, interleaving and space-time coding along multiple-transmitter/multiple-receiver diversity systems. Th...

We investigate pulse position modulation (PPM) and multipulse PPM (MPPM) for free space optical channels using bit interleaved coded modulation with iterative decoding. Data bits are first encoded by using a non recursive convolutional code and the coded bits after an interleaver are modulated before transmission. Iterative decoding is performed at the receiver. Optimized mapping is designed fo...