Employing Block Coding Research Articles

Bahl–Cocke–Jelinek–Raviv decoding algorithm applied to the three‐user binary adder channel

The Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm is a well-known maximum a posteriori probability decoding algorithm which has been proposed earlier for point to point communication applications, employing block codes or convolutional codes and turbo codes. This study describes an application of the BCJR algorithm for decoding the output of a multiple-access channel called the noisy three-user binary adder channel, in the presence of additive white Gaussian noise. The computer simulation results are presented for the overall coding performance in terms of bit error rate against signal-to-noise ratio.

The Bahl-Cocke-Jelinek-Raviv Algorithm Applied to the Two-User Binary Adder Channel

The Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm is a well known maximum a posteriori probability decoding algorithm which has been proposed earlier for point to point communication applications, employing block codes or convolutional codes, and turbo codes. This paper describes an application of the BCJR algorithm for decoding the output of a multiple access channel called the noisy two-user binary adder channel, in the presence of additive white Gaussian noise.

A High-Performance MIMO-OFDM System with Walsh Block Coding

In this paper we present a multiple-input, multiple-output (MIMO)-orthogonal frequency division multiplexing (OFDM) system that uses orthogonal Walsh sequences for block coding. Two configurations, space-time block coding (STBC) and the Vertical Bell Laboratories Layered Space-Time (V-BLAST) architecture, are considered for the proposed system. A least-squares channel estimation with the fast Fourier transform method is utilized in the system to replicate real-life scenarios. The idea of employing block coding based on orthogonal Walsh sequences is inspired by the IS-95 standard and is attempted for the first time in MIMO-OFDM systems. A simulation study is carried out by considering different antenna configurations, code sizes, and channel delays. Computer simulations show that the proposed system achieves a significant performance improvement compared to MIMO-OFDM systems that do not use the proposed block coding scheme. It is also shown that the new system is superior to some previous systems in computational complexity.

Application of forward-error correction to a Rayleigh fading h.f. communication channel

The performance is assessed of a Rayleigh fading h.f. communication channel which transmits binary data using a selection of forward-error correction systems. The criteria adopted are the probabilities of no character error, and not more than one character error in a message containing a specified number of characters, each character consisting of five information bits. The basic standards for comparison are taken to be the start/stop telegraphy mode of transmission and the synchronous transmission of pure information. The error-correction systems studied are tor, autospec and BCH(31, 21), all employing block coding. Where interleaving is applicable the improvement obtained is assessed. The advantages of employing space diversity are also assessed. The case of a constant signal is included for completeness. It is assumed that the probability of an element error is related to channel signal/noise by an exponential modem curve. The calculations are part probabilistic, part simulation. Errors and efficiency of the method are discussed.