Sequential decoding

About: Sequential decoding is a research topic. Over the lifetime, 8667 publications have been published within this topic receiving 204271 citations.

Convolutional and Tail-Biting Quantum Error-Correcting Codes

Abstract: Rate-(n-2)/n unrestricted and CSS-type quantum convolutional codes with up to 4096 states and minimum distances up to 10 are constructed as stabilizer codes from classical self-orthogonal rate-1/n F4-linear and binary linear convolutional codes, respectively. These codes generally have higher rate and less decoding complexity than comparable quantum block codes or previous quantum convolutional codes. Rate-(n-2)/n block stabilizer codes with the same rate and error-correction capability and essentially the same decoding complexity are derived from these convolutional codes via tail-biting

Free distance bounds for convolutional codes

Abstract: The best asymptotic bounds presently known on free distance for convolutional codes are presented from a unified point of view. Upper and lower bounds for both time-varying and fixed codes are obtained. A comparison is made between bounds for nonsystematic and systematic codes which shows that more free distance is available with nonsystematic codes. This result is important when selecting codes for use with sequential or maximum-likelihood (Viterbi) decoding since the probability of decoding error is closely related to the free distance of the code. An ancillary result, used in proving the lower bound on free distance for time-varying nonsystematic codes, furnishes a generalization of two earlier bounds on the definite decoding minimum distance of convolutional codes.

Soft-output decoding algorithms for continuous decoding of parallel concatenated convolutional codes

Abstract: We propose new decoding algorithms to be embedded in the iterative decoding strategy of parallel concatenated convolutional codes. They are derived from the optimum maximum-a-posteriori algorithm and permit a continuous decoding of the coded sequence without requiring trellis termination of the constituent codes. Two basic versions of the continuous algorithm and their suboptimum simplifications are described. Simulation results refer to the applications of the new algorithms to a highly efficient rate 1/3 concatenated code; they show performance only 0.6 dB worse than the Shannon limit.

The low-cost packet radio

Abstract: Research on packet switched radio networks requires reconfigurable testbeds with large numbers of readily deployable radios. This motivated the development of a small, low-cost packet radio (LPR) with the flexibility to support extensive network experiments, and to be amenable to tailoring to specific end-use applications. The LPR incorporates a digitally controlled direct sequence minimum shift keyed spread-spectrum radio and a microprocessor-based packet switch. Code changeable surface acoustic wave (SAW) matched filtering provides processing gain at burst symbol rates of 100k and 400k symbols per second in the presence of interference. Coherent recursive integration enhances synchronization performance, provides synchronous detection of the data, and serves the adaptive multipath accumulator. Forward error correction utilizing convolutional encoding and sequential decoding is incorporated at four different code rates for both burst symbol rates. The microprocessor runs the networking software. Requirements, design, and performance data for the LPR engineering model are presented.

Design of Length-Compatible Polar Codes Based on the Reduction of Polarizing Matrices

Abstract: Length-compatible polar codes are a class of polar codes which can support a wide range of lengths with a single pair of encoder and decoder. In this paper we propose a method to construct length-compatible polar codes by employing the reduction of the 2n × 2n polarizing matrix proposed by Arikan. The conditions under which a reduced matrix becomes a polarizing matrix supporting a polar code of a given length are first analyzed. Based on these conditions, length-compatible polar codes are constructed in a suboptimal way by codeword-puncturing and information-refreezing processes. They have low encoding and decoding complexity since they can be encoded and decoded in a similar way as a polar code of length 2n. Numerical results show that length-compatible polar codes designed by the proposed method provide a performance gain of about 1.0 - 5.0 dB over those obtained by random puncturing when successive cancellation decoding is employed.