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POWER AND SPECTRALLY EFFICIENT SFH-FQPSK FOR PCS APPLICATIONS

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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ERROR PROBABILITIES OF FAST FREQUENCY-HOPPED MFSK WITH NOISE-NORMALIZATION COMBINING IN A FADING CHANNEL WITH PARTIAL-BAND INTERFERENCE

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IEEE TRANSACTIONS ON COMMUNICATIONS 1992年第2期40卷 404-412页

作者： ROBERTSON, RC HA, TT Department of Electrical and Computer Engineering Code EC/RC Naval Postgraduate School Monterrey CA USA

An error probability analysis is performed for an Mary orthogonal frequency-shift keying (MFSK) communication system employing fast frequency-hopped (FFH) spread spectrum waveforms transmitted over a frequency-nonselective, slowly fading channel with partial-band interference. Diversity is obtained using multiple hops per data bit. A procedure referred to as noise-normalization combining is employed by the system receiver to minimize partial-band interference effects. Each diversity reception is assumed to fade independently according to a Rician process. The partial-band interference is modeled as a Gaussian process. Thermal noise is also included in the analysis. Forward error correction coding is applied using convolutional codes and Reed-Solomon codes. Diversity is found to dramatically reduce the degradation of the noise-normalization receiver caused by partial-band interference regardless of the strength of the direct signal component. In addition, diversity offers significant performance improvement when channel fading is strong. Further significant performance improvement is obtained for higher modulation orders (M > 2). Uncoded receiver performance with a diversity of four is roughly comparable to coded receiver performance with no diversity for ratios of bit energy-to-interference noise density in the range between roughly 12 and 22 dB. Substantial improvements in receiver performance are obtained by combining diversity, higher modulation orders, and coding.

关键词： Receivers performance boost Frequency hopping convolutional coding Error probability Fading channels frequency shift keying

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Spread spectrum multiple-access with DPSK modulation and diversity for image transmission over indoor radio multipath fading channels

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 1996年第2期6卷 200-214页

作者： Wang, BC Chang, PR Department of Communication Engineering National Chiao Tung University Hsinchu Taiwan

As demand for networked multimedia applications is increasing rapidly, it is important to provide the ubiquitous accessibility for these services in wireless communication environment, Such access allows users to share novel multimedia applications without any geographical restrictions. In this paper, we investigate the application of the well-known antimultipath spread spectrum code-division multiple access (SS-CDMA) techniques to image transmission related to the development of next-generation multimedia wireless local area networks within a building, SS-CDMA is particularly well suited to a subband coding scheme that divides the image information into multiple parallel data streams using an analysis filter bank, each of which is multiplied by its unique spreading code, All the product signals are then transmitted at the same time in the same radio channel, even though the total bandwidth of all the signals may exceed the channel bandwidth. Each received signal is independently recovered at the decoder by multiplying its spreading code and all the recovered subbands are then reassembled by a synthesis filter bank into a close reproduction to the original image, A forward error correction (FEC) scheme based on convolutional codes with interleaving is proposed to minimize the effect of bursty channel errors on the picture duality degradation, Better image quality can be achieved by using the predetection diversity combining in order to combat the indoor multipath distortion, In this paper, the image quality of subband image transmission via SS-CDMA indoor fading channels with differential phase shift keying (DPSK) modulation is evaluated and examined, Simulation results show that the image peak signal-to-noise (PSNR) ratio is inversely related to a logarithmic function of bit error rate when each subband employs equal protection channel coding.

关键词： channel coding code division multiple access convolutional codes differential phase shift keying diversity reception error correction codes fading forward error correction image coding indoor radio interleaved codes multimedia communication multipath cha fading color image information Forward error correction differential phase shift keying interleaved codes indoor radio diversity reception Image communication systems Code division multiple access image coding spread-spectrum code division multiple access convolutional coding MULTIMEDIA APPLICATION Channel coding

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Analysis and performance of bidirectional decoding of convolutional codes over fading channels

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IEEE TRANSACTIONS ON COMMUNICATIONS 1998年第10期46卷 1292-1300页

作者： Belzile, J Gagnon, F Haccoun, D Ecole Technol Super Dept Elect Engn Montreal PQ H2T 2C8 Canada Ecole Polytech Dept Elect & Comp Engn Montreal PQ H3C 3A7 Canada

In this paper, the performance of suboptimal convolutional decoding over fading channels is explored. The suboptimal decoding algorithm used is the bidirectional algorithm. By estimating a "decoder weight spectrum" for the decoder, an "equivalent free distance" may be observed. Furthermore, by using this "decoder weight spectrum," useful estimations of the error probabilities are obtained and compared to computer-simulation results in the case of very slow and very fast fading. The resultant curves are shown to be very tightly related. Computer-simulation results are also shown for various signal-to-noise ratios, normalized Doppler spreads, and frame length on three typical fading channels: the Rayleigh fading channel with exponential and Bessel autocorrelation functions and the Rician fading channel with exponential autocorrelation function, We show that considerable gains (up to 4 dB) can be obtained with respect to a similar-complexity Viterbi decoder at a frame error probability P-e = 10(-3) and a slightly smaller gain (up to 1.8 dB) at a bit error probability P-b = 10(-5).

关键词： coding/decoding convolutional coding error analysis fading channel

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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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Coded continuous phase modulation with low-complexity noncoherent reception

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IEEE TRANSACTIONS ON COMMUNICATIONS 2002年第4期50卷 517-520页

作者： Lampe, LHJ Schober, R Enzner, G Huber, JB Univ Erlangen Nurnberg D-91058 Erlangen Germany Univ Toronto Dept Elect & Comp Engn Toronto ON M5S 3G4 Canada Rhein Westfal TH Aachen Inst Commun Syst & Data Proc D-52056 Aachen Germany

Coded continuous phase modulation based on a feedback-free modulator with noncoherent detection is discussed. Low-complexity receiver processing is achieved by using only two or three linear filters for demodulation and applying noncoherent sequence estimation with reduced-state Viterbi decoding and simple branch metric calculation. Overall, the proposed noncoherent receiver provides significant advantages over recently presented approaches.

关键词： continuous phase modulation convolutional coding noncoherent sequence estimation phase-state mapping

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Medical image transmission over a GSM cellular system

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ELECTRONICS LETTERS 2000年第16期36卷 1367-1368页

作者： Perez-Sevilla, JJ McLernon, DC Univ Leeds Sch Elect & Elect Engn Inst Integrated Informat Syst Leeds LS2 9JT W Yorkshire England

This authors report on an investigation of possible source/channel coders for medical image transmission over a GSM cellular link. Two source coders (JPEG and EZW) and two channel coders (convolutional and turbo codes) are used. Analysis of the results indicates that EZW with convolutional coding gives the best performance, but some kind of automtic repeat on request (ARQ) is also needed.

关键词： Wavelet JPEG Automatic repeat request wavelets optimum performance Image communication systems convolutional coding ENCODER turbo codes

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A constraint-length based modified Viterbi algorithm with adaptive effort

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IEEE TRANSACTIONS ON COMMUNICATIONS 1999年第11期47卷 1611-1614页

作者： Feldmann, C Harris, JH San Diego State Univ Dept Elect & Comp Engn San Diego CA 92182 USA

A modified Viterbi algorithm for convolutional codes is described that provides for signal-to-noise ratio (SNR) adaptive computational effort. The algorithm has three levels of prioritized effort. Movement from one level to the next is controlled by parameters that can be selected according to desired output bit-error-rate performance. For 3-bit soft decision detected signals, coding gain within 0.06 dB of Viterbi at 3-dB SNR is achieved for the same constraint-length code with modest parameter values and computational effort. At values of SNR above 6 dB, the algorithm decodes with very low computational effort. Effort levels are controlled by spanning the decoding trellis in steps that are one constraint-length long.

关键词： Fishing power DEcoding Self tuning Viterbi algorithm bit error rate performance coding gain convolutional coding

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

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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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A personal history of the Viterbi algorithm

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IEEE SIGNAL PROCESSING MAGAZINE 2006年第4期23卷 120-+页

作者： Viterbi, Andrew J. Universidad Carlos III de Madrid MADRID Spain

This paper describes how Andrew J. Viterbi developed a non-sequential decoding algorithm which proved useful in showing the superiority of convolutional codes over block codes for a given degree of decoding complexity. The Viterbi algorithm is now used in most digital cellular phones and digital satellite receivers as well as in such diverse fields as magnetic recoding, voice recognition, and DNA sequence analysis.

关键词： Viterbi decoding block codes computational complexity convolutional codes history Viterbi algorithm decoding complexity nonsequential decoding algorithm Social history convolutional coding complexity classes Viterbi algorithm digital cellular phone Block codes digital satellite receiver Viterbi decoding

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