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A DIVERSITY COMBINING DS/CDMA SYSTEM WITH convolutional ENcoding AND VITERBI DEcoding

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 1995年第2期44卷 304-312页

作者： SOUISSI, S WICKER, SB GEORGIA INST TECHNOL SCH ELECT & COMP ENGNCODING & INFORMAT THEORY LABATLANTAGA 30332

Averaged diversity combining is applied to an asynchronous DS/CDMA system using convolutional encoding and Viterbi decoding, A CRC code is included in the scheme to trigger retransmission requests, Multiple received packets are combined on a bit by bit basis to form a single, more reliable packet, The error correcting decoder operates on the combined packet, as opposed to the most recently received individual packet (e.g., as in a type-I hybrid ARQ protocol), substantially increasing the probability of acceptance with each additional transmission, We show that the proposed technique allows a significant increase in the CDMA system capacity, throughput, and reliability.

关键词： ACCEPTANCE Packet Cyclic redundancy check convolutional coding Binary digits RETRANSMISSION Viterbi decoding diversity reception

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PERFORMANCE OF convolutional coding WITH SYMBOL ERASURE FOR QPSK FREQUENCY-SELECTIVE FADING CHANNELS

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IEICE TRANSACTIONS ON COMMUNICATIONS 1993年第2期E76B卷 139-147页

作者： ZHOU, H DENG, RH NATL UNIV SINGAPORE DEPT ELECT ENGN SINGAPORE 0511 SINGAPORE NATL UNIV SINGAPORE DEPT ELECT & COMP ENGN SINGAPORE 0511 SINGAPORE

In this paper, we study the performance of convolutional coding using an error-and-erasure correction Viterbi decoder for pi/4-shift QDPSK mobile radio transmission. The receiver uses received signal envelope as channel state information to erase unreliable symbols instead of making explicit decision before decoding. The performance study is carried out over frequency-selective fading channel with additive white Gaussian noise, co-channel interference and propagation delay spread. The results show that decoding with symbol erasure can significantly improve the system transmission performance compared to decoding without symbol erasure.

关键词： FREQUENCY-SELECTIVE FADING convolutional coding ERROR-AND-ERASURE CORRECTION VITERBI DEcoding

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PERFORMANCE ENHANCEMENT USING FORWARD ERROR-CORRECTION ON POWER-LINE COMMUNICATION CHANNELS

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IEEE TRANSACTIONS ON POWER DELIVERY 1994年第2期9卷 645-653页

作者： CHAN, MHL FRIEDMAN, D DONALDSON, RW UNIV BRITISH COLUMBIA DEPT ELECT ENGNVANCOUVER V6T 1Z4BCCANADA

The use of forward error correction (FEC) coding is investigated, to enhance communication throughput and reliability on noisy power line networks. Rate one-half self-orthogonal convolutional codes are considered. These codes are known to be effective in other environments, and can be decoded inexpensively in real-time using majority logic decoders. Extensive bit and packet error rate tests were conducted on actual, noisy in-building power line links. coding gains of 15 dB were observed at 10(-3) decoded bit error rates. A self-orthogonal (2, 1, 6) convolutional code with interleaving to degree 7 was particularly effective, and was implemented as a VLSI microelectronic chip. Its use improved data throughput and packet error rates substantially, at data transmission rates of 9,600 bits/s.

关键词： POWERLINE COMMUNICATIONS FORWARD ERROR CORRECTION (FEC) coding convolutional coding DISTRIBUTION AUTOMATION VLSI CODEC IMPLEMENTATION BIT ERROR RATE MEASUREMENT PACKET ERROR RATE MEASUREMENT DATA THROUGHPUT MEASUREMENT

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POWER AND SPECTRALLY EFFICIENT SFH-FQPSK FOR PCS APPLICATIONS

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 1994年第3期43卷 795-800页

作者： GUO, YP FEHER, K UNIV CALIF DAVIS DIGCOM INCDEPT ELECT ENGNDAVIS & CONSULTING GRPDAVISCA 95616

A power and spectrally efficient slow frequency hopping FQPSK (SFH-FQPSK) is proposed for future personal communications systems (PCS). We apply the constant envelope FQPSK modem/radio architecture (Filtered QPSK [7]) to a slow frequency hopping system to achieve higher spectrum efficiency as well as higher power efficiency. Being a constant envelope system, SFH-FQPSK can operate with class C power amplifier without output backoff (OBO). Therefore;it is 4-7 dB more power efficient than TM-QPSK which is currently adopted as the US digital cellular and Japanese handyphone PCS standards. As compared to the European DECT and GSM standard GMSK, the proposed SFH-FQPSK is about 50% more spectrally efficient. The BER performance of this system, employing convolutional coding and Viterbi decoding for;FEC, is evaluated in a Rayleigh fading/AWGN environment. Results show that the BER performance of our hard-limited SFH/FQPSK is as good as that of linear SFH coherent QPSK (SFH-CQPSK), and is 3 and 5 dB better than ideal Coherent QPSK and differentially encoded coherent QPSK (DEQPSK) systems, respectively. With the higher spectral and power efficiency and superior BER performance, we conclude that the proposed SFH-FQPSK is an excellent candidate for the future high-capacity PCS networks.

关键词： spectral efficiency Quadrature phase shift keying bit error rate performance dynamic efficiency POWER CONVERSION SYSTEM Viterbi decoding Personal communication systems slow frequency hopping convolutional coding

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IMPROVED HF MODEM USING convolutional coding

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ELECTRONICS & COMMUNICATION ENGINEERING JOURNAL 1992年第2期4卷 73-82页

作者： HONARY, B ZOLGHADR, F DARNELL, M MAUNDRELL, M UNIV HULL DEPT ELECTR ENGNHULL HU6 7RXN HUMBERSIDEENGLAND ROYAL AIRCRAFT ESTAB CTR DEF RES AGCYFARNBOROUGH GU14 6TDHANTSENGLAND

The paper describes the design of a digitally implemented modem for use over HF (2-30 MHz) radio channels. As a completely digital approach offers the prospect of a number of significant improvements, a new digital multifrequency-shift-keying (MFSK) modem has been developed that employs a novel digital processing procedure termed code-assisted bit synchronisation (CABS). Signal detection is achieved via a set of noncoherent correlators, whilst symbol synchronisation and error correction are performed using a soft-decision Viterbi decoder. Practical tests of the modem show that it operates effectively under both additive white Gaussian noise and real HF channel conditions.

关键词： error correction frequency shift keying digital radio modem Codes 2 to 30 MHz additive white Gaussian noise convolutional coding digital multifrequency-shift-keying real HF channel conditions digital radio systems encoding signal detection Other telecommunication terminals and equipment Radio links and equipment soft-decision Viterbi decoder modems noncoherent correlators synchronisation code-assisted bit synchronisation symbol synchronisation

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Error probabilities of FFH/BFSK with noise normalization and soft decision Viterbi decoding in a fading channel with partial-band jamming

Error probabilities of FFH/BFSK with noise normalization and...

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作者： Chua, Anthony Y. P. NAVAL POSTGRADUATE SCHOOL

学位级别：硕士

An error probability analysis of a communications link employing convolutional coding with soft decision Viterbi decoding implemented on a fast frequency-hopped, binary frequency-shift keying (FFH/BFSK) spread spectrum system is performed. The signal is transmitted through a frequency non-selective, slowly fading channel with pa1tial-band jamming. Noise nomialization combining is employed at the receiver to alleviate the effects of par'tial-band jamming. The received signal amplitude of each hop is modeled as a Rician process, and each hop is assumed to fade independently. It is found that with the implementation of soft decision Viterbi decoding that the performance of the receiver is improved dramatically when the coded bit energy to partial-band noise power spectral density ratio (Eb/N1) is greater than 10dB. At higher Eb/NI, the asymptotic error improves dramatically and vanes from 105 to 10'" depending on the constraint length (V), number of hops/bit (L), and the strength of the direct signal (012/202). In addition, nearly worst case jamming occurs when lhe jammer uses a full band jamming strategy, even when L: l and there is a very strong direct signal (Q2/203 = I00). Due to non-coherent combining losses, when the hop per bit ratio is increased, there is some degradation at moderate Eb/NI. Furthermore, when a stronger code is used (ie., the constraint length is longer), performance improves, especially for high ED/N, where the asymptotic error is reduced. Finally, soft decision decoding improves performance over hard decision decoding from 4 to 8dB at moderate Eb/N, depending on the code rate and with a much lower asymptotic error at high Eb/N1.

关键词： fast frequency hopping noise normalization convolutional coding

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PERFORMANCE OF A SATELLITE MODEM TRANSMITTING convolutionalLY AND DIFFERENTIALLY ENCODED 8PSK SIGNALS

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INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS 1993年第1期11卷 19-32页

作者： CLARK, AP CHEUNG, SW LOUGHBOROUGH UNIV TECHNOL DEPT ELECT & ELECTR ENGNLOUGHBOROUGH LE11 3TULEICSENGLAND

The paper studies a digital satellite modem for mobile systems. The modem transmits a convolutionally and differentially encoded eight-phase-shift-keyed (CDE8PSK) signal over a satellite link and employs a near-maximum-likelihood decoder at the receiver. The signal can tolerate phase ambiguities that are multiples of pi/4 radians, which normally result from the carrier recovery loop at the receiver. However, the carrier recovery loop is not considered here. The high-power amplifier (HPA) at the earth-station transmitter may introduce non-linear distortion to the CDE8PSK signal, and predistortion may or may not be used. Several different earth-stations are assumed to have simultaneous access to a given transponder on the satellite, in an arrangement of frequency division multiple access, but the satellite transponder is assumed to be linear. Thus the CDE8PSK signals that occupy the immediately adjacent frequency bands can introduce adjacent-channel interference (ACI) to the desired CDE8PSK signal. Extensive computer-simulation tests have been carried out to evaluate the effects of non-linear distortion with predistortion, in the presence of ACI, on the tolerance of the modem to additive white Gaussian noise. Four different bandwidths of the transmitted signal are considered, together with three different arrangements of the demodulator. The predistorter operates on the baseband signal at the input to the modulator and assumes a prior knowledge of the HPA characteristics. In all simulation tests, an equivalent baseband model of the transmission system is used, and the results are used to determine the preferred modem design.

关键词： MODEM NEAR-MAXIMUM-LIKELIHOOD DEcoding convolutional coding DIFFERENTIAL ENcoding CODED PSK SIGNAL ACI PREDISTORTION

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ERROR-PROBABILITY FOR REPEAT REQUEST SYSTEMS WITH convolutional-CODES

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IEEE TRANSACTIONS ON INFORMATION THEORY 1993年第5期39卷 1680-1684页

作者： KUDRYASHOV, BD Department of Automatic Control Systems St. Petersburg Institute of Aviation Instrument Making Saint Petersburg Russia

A new decoding algorithm based on the modified Viterbi algorithm for repeat request systems is considered. A new asymptotic error probability bound is derived. It is shown that the error exponent for convolutional coding can be related to the exponent for block coding by a graphical method known as inverse concatenation construction.

关键词： REPEAT REQUEST SYSTEM convolutional coding VITERBI ALGORITHM ERROR PROBABILITY EXPONENT

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QUANTIZATION LOSS IN convolutional DEcoding

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IEEE TRANSACTIONS ON COMMUNICATIONS 1993年第2期41卷 261-265页

作者： ONYSZCHUK, IM CHEUNG, KM COLLINS, O JOHNS HOPKINS UNIV DEPT ELECT ENGNBALTIMOREMD 21218 JET PROP LAB PASADENACA 91109

We study the loss in quantizing coded symbols from the AWGN channel with BPSK or QPSK modulation. A new quantization scheme and branch metric calculation method are presented. For the uniformly quantized AWGN channel, cutoff rate is used to determine the stepsize and the smallest number of quantization bits needed for a given bit signal-to-noise ratio (E(b)/N0) loss. A 9-level quantizer is presented, along with 3-bit branch metrics for a rate 1/2 code, which causes an E(b)/N0 loss of only 0.14 dB. These results also apply to soft-decision decoding of block codes. A tight upper bound is derived for the range of path metrics in a Viterbi decoder. The calculations are verified by simulations of several convolutional codes, including the new memory 14, rate 1/4 or 1/6 codes used by the big Viterbi decoders at JPL.

关键词： computational methods Quantization Viterbi decoders Binary phase shift keying step size Quadrature phase shift keying quadrature phase soft-decision decoding quantizer convolutional coding AWGN channels AWGN

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Concatenated coding scheme with variable coding gain

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Electronics and Communications in Japan (Part III: Fundamental Electronic Science) 1993年第3期76卷 91-104页

作者： Kojima, Toshiharu Fujimura, Akinori Miyake, Makoto Fujino, Tadashi Yoshida, Hideo Yamagishi, Atsuhiro Communication Systems Laboratory Mitsubishi Electric Corporation Kamakura 247 Japan Computer and Information Systems Laboratory Mitsubishi Electric Corporation Kamakura 247 Japan

The concatenated coding scheme using convolutional coding with Viterbi decoding for inner code and Reed‐Solomon (RS) code for outer codes is an attractive scheme that can achieve a coding gain larger than that of the convolutional coding with the Viterbi decoding scheme. Hence, it has attracted attention in a wide range of fields in satellite communications from space communications to digital image transmission systems. This paper presents the configuration and characteristics of a newly developed concatenated coding scheme with variable coding gain. This scheme enables selection of a coding gain considering the signal processing time of coding and decoding by enabling selection of: 1) the block length of the RS code (and its error‐correction capability);2) the depth of interleaving combining the inner and outer code by a single codec. In addition, in this scheme, a new synchronization word detection method was developed and employed. In this method, nonlinear conversion is applied to soft decision demodulated data to synchronize the RS codeword and interleaving. It has been confirmed by numerical calculations that this synchronization word detection method has characteristics further improved over those of the conventional soft decision synchronization word detection method which is superior to the hard decision method. An experimental system was developed and the field test via Ka‐band satellite of communication satellite No. 3 (CS‐3) was performed, and the tradeoff relationships between the coding/decoding signal processing time and coding gain have been clarified quantitatively. Copyright © 1993 Wiley Periodicals, Inc., A Wiley Company

关键词： Concatenated code convolutional coding Reed‐Solomon code synchronization word detection Viterbi decoding

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