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作者： Michael W. Briske Naval Postgraduate School

学位级别：硕士

Research entails derivation of statistical description of output from an MFSK receiver which uses self-normalization of the output from quadratic detectors. The system uses fast frequency hopping to provide diversity and assumes independent channels for each hop when the signal is recombined. The effects of fading channels are investigated for both Rayleigh and Rician fading channel descriptions. Probability of bit error for the uncoded performance is plotted for various signal-mt-noike ratin.% (SNR) and different levels of diversity versus worst-case partial-band jamming. Analysis for Forward Error Correction coding is included for rate 1/2 and 1/3 convolutional codes and (n, k) Reed-Solomon Block codes. Probability of bit error is plotted for each code with various signal-to-noise ratios and diversity levels I to 4 versus worst-case partial-band jamming.

关键词： MFSK self-normalization receiver Reed-Solomon coding convolutional coding fading path partial-band interference

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INTERLEAVED convolutional coding FOR THE TURBULENT ATMOSPHERIC OPTICAL COMMUNICATION CHANNEL

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IEEE TRANSACTIONS ON COMMUNICATIONS 1988年第9期36卷 993-1003页

作者： DAVIDSON, FM KOH, YT Department of Electrical and Computer Engineering The Johns Hopkins University Baltimore MD USA

The coding gain of a constraint-length-three, rate one-half convolutional code over a long clear-air atmospheric direct-detection optical communication channel using binary pulse-position modulation signalling is directly measured as a function of interleaving delay for both hard- and soft-decision Viterbi decoding. Maximum coding gains theoretically possible for this code with perfect interleaving and physically unrealizable perfect-measurement decoding were about 7 dB under conditions of weak clear-air turbulence, and 11 dB at moderate turbulence levels. The time scale of the fading (memory) of the channel was directly measured to be tens to hundreds of milliseconds, depending on turbulence levels. Interleaving delays of 5 ms between transmission of the first and second channel bits output by the encoder yield coding gains within 1.5 dB of theoretical limits with soft-decision Viterbi decoding. coding gains of 4-5 dB were observed with only 100 mu s of interleaving delay. Soft-decision Viterbi decoding always yielded 1-2 dB more coding gain than hard-decision Viterbi decoding.

关键词： attenuation memory decibel coding gain Viterbi decoding Optical communication Turbulent Flow convolutional coding soft decision dubnium MILLISECOND

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AN UPPER BOUND ON THE BIT ERROR-PROBABILITY OF COMBINED convolutional coding AND CONTINUOUS PHASE MODULATION

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IEEE TRANSACTIONS ON INFORMATION THEORY 1988年第5期34卷 1263-1269页

作者： LINDELL, G SUNDBERG, CEW Telecommunication Theory University of Lund Lund Sweden Telecommumcation Theory University of Lund Lund Sweden AT and T Bell Laboratories Inc. Murray Hill NJ USA

The bit error probability properties of signals consisting of convolutional coding combined with partial-response multilevel continuous phase modulation (CPM) are studied. It is assumed that the channel is an additive white Gaussian noise channel and that the receiver performs coherent maximum-likelihood sequence detection by means of the Viterbi algorithm. An upper bound on the bit error probability is derived, using the average generating function technique, and evaluated numerically for a number of coded multilevel full-response CPM schemes. Simulation results are also presented. It is concluded that the free Euclidean distance is the best one-parameter description of the error probability for the considered class of signals for high signal-to-noise ratios. However, the upper bound results show that the free distance alone yields pessimistic bit error probability behavior for some interesting cases.

关键词： bit error probability continuous phase modulation Upper bound Error probability Viterbi algorithm signals AWGN channels convolutional coding

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HAMMING DISTANCE PRESERVING MAPPINGS AND TRELLIS CODES WITH CONSTRAINED BINARY SYMBOLS

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IEEE TRANSACTIONS ON INFORMATION THEORY 1989年第5期35卷 1098-1103页

作者： FERREIRA, HC WRIGHT, DA NEL, AL SAN DIEGO STATE UNIV DEPT ORNAMENTAL HORT SAN DIEGO CA 92182 USA

The transformation of a linear convolutional code into a run-length-constrained or balanced trellis code with the same or larger free distance is investigated. The transformation involves a Hamming-distance-preserving mapping of the set of unconstrained binary symbols of the convolutional code onto a set of suitably constrained symbols. Simple tests to determine if these mappings can exist and a tree search algorithm for finding such mappings are presented.

关键词： Signs and symbols Binary Trellis codes convolutional coding SEARCHING ALGORITHM Hamming distance

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FURTHER-STUDIES ON EFFICIENT AFEC SCHEMES FOR KA-BAND SATELLITE SYSTEMS

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 1989年第1期25卷 9-20页

作者： KHAN, MH LENGOC, T BHARGAVA, VK CONCORDIA UNIV DEPT ELECT & COMP ENGNMONTREAL H3G 1M8QUEBECCANADA UNIV VICTORIA DEPT ELECT ENGNVICTORIA V8W 2Y2BCCANADA

Adaptive fade margin is required to counter the severe but varying rain attenuation in Ka satellite communications. In searching for a suitable rain countermeasure, the effectiveness of the adaptive forward error control (AFEC) scheme is studied. Two AFEC schemes using convolutional codes and concatenated codes are proposed and their performance analyzed. The schemes can provide a progressively adaptive fade margin of 10.1 and 10.4 dB, respectively, in excess of the systems fixed fade margin. To improve the efficient use of shared resources of the system, an AFEC scheme using double coding is introduced, and its performance is analyzed. In this scheme a single codec is used repeatedly, and as a result the hardware cost is reduced and the utilization increased. The effective usable capacity of a conceptual AFEC resource sharing scheme using Golay double coding is also analyzed.

关键词： Tumor margin status Effective Capacity coding Concatenated codes Scheme Self tuning Satellite systems Resource sharing convolutional coding rain attenuation Satellite communication

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LIMITING ERROR PROPAGATION IN VITERBI DEcoding OF convolutional-CODES

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IEEE TRANSACTIONS ON INFORMATION THEORY 1989年第6期35卷 1295-1299页

作者： LEONARD, DA RODGER, CA Department of Algebra Combinatorics and Analysis Aubum University Auburn AL USA

The problem of avoiding infinite error propagation in noncatastrophic convolutional codes when using a truncated Viterbi decoder is considered. A truncation length tau is defined in terms of walks in the state diagram. The truncation length guarantees that, in the presence of a sufficiently long guard space, a truncated Viterbi decoder will always recover from any error event. This value of tau is the theoretically smallest possible truncation length.

关键词： Error propagation Viterbi decoders Cutoffs walking convolutional coding

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AN EFFICIENT MAXIMUM-LIKELIHOOD DEcoding ALGORITHM FOR GENERALIZED TAIL BITING convolutional-CODES INCLUDING QUASICYCLIC CODES

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IEEE TRANSACTIONS ON COMMUNICATIONS 1989年第8期37卷 875-879页

作者： WANG, Q BHARGAVA, VK Department of Electrical and Computer Engineering University of Victoria Victoria BC Canada

The complexity of the algorithm is shown to be asymptotically equal to that of the Viterbi algorithm and is very close for practical noisy channels. The latter is shown by means of computer simulation. The algorithm can be applied directly in an environment where soft-decision decoding is required or preferred. However, depending on the environment, some simplifications may be possible and/or necessary, resulting in suboptimal algorithms. Codes suitable for use with the algorithm should have short total memory length.

关键词： Environments maximum likelihood decoding soft-decision decoding maximum likelihood algorithms convolutional coding tail biting Viterbi algorithm Codes

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A FAST ALGORITHM FOR COMPUTING DISTANCE SPECTRUM OF convolutional-CODES

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IEEE TRANSACTIONS ON INFORMATION THEORY 1989年第6期35卷 1146-1159页

作者： CEDERVALL, M JOHANNESSON, R Dept. of Inf. Theory Lund Univ. Sweden Department of Information Theory University of Lund Lund Sweden

A fast algorithm for searching a tree (FAST) is presented for computing the distance spectrum of convolutional codes. The distance profile of a code is used to limit substantially the error patterns that have to be searched. The algorithm can easily be modified to determine the number of nonzero information bits of an incorrect path as well as the length of an error event. For testing systematic codes, a faster version of the algorithm is given. FAST is much faster than the standard bidirectional search. On a microVAX, d/sub infinity /=27 was verified for a rate R=1/2, memory M=25 code in 37 s of CPU time. Extensive tables of rate R=1/2 encoders are given. Several of the listed encoders have distance spectra superior to those of any previously known codes of the same rate and memory. A conjecture than an R=1/2 systematic convolutional code of memory 2M will perform as well as a nonsystematic convolutional code of memory M is given strong support.

关键词： Spectra Fasting A* Algorithm Codes algorithms error model ENCODER CPU time GPR17 protein, human convolutional coding

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THERE ARE MANY GOOD PERIODICALLY TIME-VARYING convolutional-CODES

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IEEE TRANSACTIONS ON INFORMATION THEORY 1989年第2期35卷 460-463页

作者： LEE, PJ Bell Commun. Res. Morristown NJ USA

It is shown empirically that the number of good periodically time-varying convolutional codes increases exponentially with the period for any set of parameters. Hence, they can be used to enhance the security of cryptosystems without sacrificing error correction capability. It is shown that some periodically time-varying convolutional codes improve the free distance compared with fixed codes.

关键词： time varying error correction capability convolutional coding cryptography

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CHANNEL coding FOR SATELLITE MOBILE CHANNELS

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INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS 1989年第3期7卷 143-163页

作者： WONG, KHH HANZO, L STEELE, R Department of Electronics and Computer Science University of Southampton Southampton SO9 5NH U.K.

The deployment of channel coding and interleaving to enhance the bit-error performance of a satellite mobile radio channel is addressed for speech and data transmissions. Different convolutional codes (CC) using Viterbi decoding with soft decision are examined with inter-block interleaving. Reed-Solomon (RS) codes with Berlekamp-Massey hard decision decoding or soft decision trellis decoding combined with block interleaving are also investigated. A concatenated arrangement employing RS and CC coding as the outer and inner coders, respectively, is used for transmissions via minimum shift keying (MSK) over Gaussian and Rayleigh fading channels. For an interblock interleaving period of 2880 bits, a concatenated arrangement of an RS(48,36). over the Galois field GF(256) and punctured PCC(3,1,7) yielding an overall coding rate of 1/2, provides a coding gain of 42dB for a BER of 10 −6 , and an uncorrectable error detection probability of 1–10 −9 .

关键词： Channel coding Mobile satellite channels convolutional coding Reed-Solomon coding Interleaving Trellis decoding of block codes

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