Simplified method for the construction of an orthonormal base forCPFSK signals

The authors present a simplified method to derive a 2M dimensional orthonormal base for M-ary CPFSK signals based on the well-known Gram-Schmidt procedure. On the basis of this method, the simulated bit error performance of 4, 8 and 16-ary CPFSK modulation in additive white Gaussian noise channels is presented     

Woven codes with outer warp: variations, design, and distanceproperties

We consider convolutional and block encoding schemes which are variations of woven codes with outer warp. We propose methods to evaluate the distance characteristics of the considered codes on the basis of the active distances of the component codes. With this analytical bounding technique, we derived lower bounds on the minimum (or free) distance of woven convolutional codes, woven block codes, serially concatenated codes, and woven turbo codes. Next, we show that the lower bound on the minimum distance can be improved if we use designed interleaving with unique permutation functions in each row of the warp of the woven encoder. Finally, with the help of simulations, we get upper bounds on the minimum distance for some particular codes and then investigate their performance in the Gaussian channel. Throughout this paper, we compare all considered encoding schemes by means of examples, which illustrate their distance properties     

Partially concatenated convolutional codes

We present a new concatenated code construction. The resulting codes can be viewed as intermediate between parallel and serially concatenated convolutional codes. Proper partitioning of the outer code sequence provides a new degree of freedom for code design. Various methods are considered to analyze code properties.     

Simulated error performance of encoded MSK signals in Gaussian andRician fading channels

New trellis codes are constructed that are based on binary concordant convolutional codes and minimum shift keying. The codes are investigated in various communication channels by means of computer simulation     

Generalized concatenation of encoded tamed frequency modulation

A novel construction for encoded tamed frequency modulation (TFM) is introduced which is based on the principles of generalized concatenation. The inner TFM is partitioned into nested subsystems which increases the free Euclidean distances. In order to obtain a large distance among the nested TFM subsystems, the scrambler matrices have to be computed which transfer the original TFM into the equivalent TFM with better partitioning properties. Then outer convolutional codes with different error-correcting capabilities are used to protect the partitioning. The new concatenated and generalized concatenated constructions were simulated in an additive white Gaussian noise channel. A multistep decoding algorithm based on soft-output demodulation was used. We present various simulation results which show a significant coding gain in comparison with the best known trellis codes having the same trellis state complexity     

Space-Time Code Construction Using the Code Factorization Technique

A space-time block code construction is presented which achieves maximum diversity for multi-antenna transmission. The construction is based on selected cyclotomic cosets of an extension field which are multiplied together to give a set of transformation polynomials. A space-time factorization code [1] can be constructed by encoding the information vector by different polynomials to form a set of codeword matrices. Codes are constructed over the Galios field GF(2) and mapped to the BPSK signal constellation. The effect of this mapping on the code design criteria is investigated. Simulation results are compared with the statistical properties of the codes based on the design criteria from [2] and [3].     

Partitioning of convolutional codes using a convolutional scrambler

Recently a partitioning method for convolutional codes of rate 1/N has been proposed. The authors investigate an improved partitioning scheme, which is illustrated by a code with small constraint length. This new method leads to better free distances in the partitioned subcodes     

Performance of generalised concatenated codes on fading channels

Generalised concatenated codes based on a partial unit memory (PUM) inner code and Reed-Solomon (RS) outer codes are investigated on the perfectly interlayed frequency-nonselective slowly fading channel. The specific structure of the concatenated coding schemes makes them highly attractive for such an application.<>     

Woven Coded CPFSK With Hierarchical Code Structure

We introduce hierarchical woven coded continuous phase frequency-shift keying (hierarchical WCCPFSK) as the serial concatenation of different outer convolutional codes and inner CPFSK. We compare it to WCCPFSK with identical outer convolutional codes. With the proposed code combinations, hierarchical WCCPFSK achieves superior decoding capability. Simulations show that it performs better at medium SNRs.