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We investigate a binary code, which is implemented by serially concatenating a multiplexer, a multilevel delay processor, and a signal mapper to a binary turbo encoder. To achieve improved convergence behavior, we modify the binary code by passing only a fraction of the bits in the turbo code through the multilevel delay processor and the signal mapper. Two decoding [ABSTRACT FROM AUTHOR]

In this letter, we propose a tow complexity Maximum Likelihood (ML) decoding algorithm for orthogonal space-time block codes (OSTBCs) based on the real-valued lattice representation and QR decomposition. We show that for a system with rate = K/T, where K is the somber of transmitted symbols per T time slots, the proposed algorithm decomposes the original complex-valued system into a parallel system represented by 2K real-valued components, thus allowing for a simple and independent detection of the real and imaginary parts of each complex transmitted symbol. We further show that for square L-QAM constellations, the proposed algorithm reduces the decoding computational complexity from O(L) for conventional ML to C'(√L) without sacrificing the performance. [ABSTRACT FROM AUTHOR]

In this paper, we propose orthogonal Space-Time (ST) codes for binary Pulse Position Modulations (PPM). Unlike the well known orthogonal ST codes, the proposed schemes verify the additional constraint of achieving a foil transmit diversity order without introducing any phase rotations. This renders the proposed codes suitable for Free-Space Optical (FSO) communications with direct detection and for Ultra-WideBand (UWB) communications. At the receiver side, optimal detection can he achieved with linear operations and the proposed codes can be also applied with On-Off Keying (OOK). [ABSTRACT FROM AUTHOR]

In this paper, we explain how to build a turbo-like structure with binary inputs and chaotic outputs for efficient coding and decoding in additive white Gaussian noise (AWGN). We analyze the convergence of the decoding algorithm, the performance in the error floor region and explain minimum distance properties of the resulting codes. [ABSTRACT FROM AUTHOR]

In this letter, a tow complexity decoding algorithm for binary linear block codes is applied to low-density parity-check (LDPC) codes and improvements are described, namely an extension to soft-decision decoding and a loop detection mechanism. For soft decoding, only one real-valued addition per code symbol is needed, while the remaining operations are only binary as in the hard decision case. The decoding performance is considerably increased by the loop detection. Simulation results are used to compare the performance with other known decoding strategies for LDPC codes, with the result that the presented algorithms offer excellent performances at smaller complexity. [ABSTRACT FROM AUTHOR]