Dual-k Codes Research Articles

Coded modulation for digital communications over Rayleigh fading channels

A signal-design method based on the integration of coding and modulation, noncoherent demodulation, and soft-decision decoding is described. The integrated coding/modulation approach provides robust signal designs for digital communications over rapidly fading channels that may be encountered in medium- and long-range, horizontal-path acoustic telemetry. The structure of the corresponding demodulator/decoder is described, and the error rate performance of the resulting system is evaluated for Rayleigh fading signal statistics. Of special interest is the use of concatenated coding for forming codes of large distance, and an example is given using dual-k codes. The performance gains that are achieved by the integrated coded modulation approach relative to conventional uncoded signal designs are also illustrated. >

Two classes of convolutional codes over GF(q) for q-ary orthogonal signaling

Two classes of nonbinary convolutional codes for error control in communication systems employing q-ary orthogonal signaling are discussed. These classes include as special cases, the dual-k codes and the codes treated by B.D. Trumpis (1975). The types of code, extensions of previous bounds on free distance, the noncatastrophic condition for these codes, and conditions for catastrophic error propagation are described. Codes obtained by a computer search, optimal in that the truncated transfer function bound on the probability of symbol error is minimized, are presented. It is shown how good convolutional codes can be constructed from cyclic block codes. The performance of some of these codes over additive white Gaussian noise channels, Rayleigh channels, and partial-band interference channels is also discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Performance of Concatenated Dual-k Codes on a Rayleigh Fading Channel with a Bandwidth Constraint

The error rate performance, obtained on a Rayleigh fading channel, is determined and illustrated graphically for concatenated codes in which the outer code is a dual- k convolutional code and the inner code is either a Hadamard block code or a block orthogonal code. Comparison of the performance of these two types of concatenated codes is made on the basis of the same bandwidth utilization. It is also illustrated that the concatenated dual- k code yields a significant improvement in performance relative to the performance achieved with the inner code alone.