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A new target response with parity coding for high density magnetic recording channels

IEEE TRANSACTIONS ON MAGNETICS 1998年第4期34卷 2382-2386页

作者： Conway, T Analog Devices BV Limerick Ireland

In this paper, a modified equalization target is proposed for the high density magnetic recording channel. This target is a closer match to the channel than the EEPR4 response and hence has better detection performance, Based on the dominant error events for this target, a parity-based coding scheme is also proposed to achieve a coding gain with the modified target. The use of the parity code detects the occurrence of the dominant error events while achieving a high code rate. The detection system consists of a Viterbi detector matched to the channel response and a post processor to handle the code constraints. This system is shown to perform well compared to other proposed detection systems through analysis and simulation on a Lorentzian based channel model.

关键词： digital magnetic recording equalizers modulation coding partial response signaling trellis codes Viterbi decoding

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VLSI for OFDM

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IEEE COMMUNICATIONS MAGAZINE 1998年第10期36卷 127-131页

作者： Weste, N Skellern, DJ Macquarie Univ Sydney NSW 2109 Australia

This article discusses the VLSI implications of high-speed coded orthogonal frequency-division multiplexing modulation. This is achieved by looking at practical examples of the computational blocks that constitute a C... 详细信息

关键词： Very large scale integration OFDM modulation Frequency division multiplexing Modems Intersymbol interference modulation coding Bandwidth Delay effects Frequency modulation Computer networks

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Joint design of a channel-optimized quantizer and multicarrier modulation

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IEEE TRANSACTIONS ON COMMUNICATIONS 1998年第10期46卷 1254-1257页

作者： Ho, KP Kahn, JM Chinese Univ Hong Kong Dept Informat Engn Shatin NT Peoples R China Univ Calif Berkeley Dept Elect Engn & Comp Sci Berkeley CA 94720 USA

We present an algorithm for design of a joint source-channel coder using a channel-optimized quantizer and multicarrier modulation, By changing the power of each subchannel in the multicarrier modulation system, different degrees of error protection can be provided for different bits according to their importance. The algorithm converges to a locally optimum system design. Compared to a Lloyd-Max scalar quantizer or a LEG vector quantizer using single-channel transmission, our optimized code can yield substantial performance improvements. The performance improvements are most pronounced at low channel signal-to-noise ratios.

关键词： modulation coding Algorithm design and analysis Power system protection Signal to noise ratio Vector quantization Channel coding Transmitters Design optimization Bit error rate Simulated annealing

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On timing recovery from full-wave-rectified magnetic signals

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IEEE TRANSACTIONS ON MAGNETICS 1998年第1期34卷 91-93页

作者： Melas, CM Thapar, HK IBM Almaden Research Center Datapath Systems Corporation

Fullwave rectified magnetic readback signals have a frequency component at the bit frequency, which can be utilized for timing. Feedforward timing can provide quick bit resync when recovering from thermal asperities, since it doesn't depend on a sync field. To be usable, the timing phase must vary little with the binary data, and the timing signal amplitude range must be reasonable. We compute the phase and amplitude distributions for all periodic patterns of length 9, as well as for PRES patterns. We conclude that the lower the signal ISI, the smaller the timing phase shift. A rate 8/9 code reduces the timing shift to 2% for PR4, 5% for EPR4. Uncoded PRES signals produce less than 2% timing shift.

关键词： Timing Frequency Intersymbol interference Magnetic flux Clocks modulation coding Pulse modulation Pulse shaping methods Shape Polynomials

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The globalstar cellular satellite system (vol 46, pg 935, 1998)

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IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 1998年第8期46卷 1244-1244页

作者： Dietrich, FJ Monte, P Metzen, P Space Syst Loral Palo Alto CA USA Globastar San Jose CA 95164 USA

The Globalstar cellular-telephone satellite system is described, including its use of code-division multiple access (CDMA) as the basic modulation scheme. Use of diversity for signal quality as well as power control is described, Development of the complex array antennas for L-band (1.6 GHz) and S-band (2.5 GHz) communication with the hand-held radios is described in detail.

关键词： Satellite broadcasting Multiaccess communication Mobile communication Telephony Artificial satellites Satellite ground stations Downlink Circuits Frequency conversion modulation coding

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Principal ratio combining for fixed wireless applications when transmitter diversity is employed

Principal ratio combining for fixed wireless applications wh...

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IEEE International Conference on Universal Personal Communications (ICUPC 98)

作者： Tarokh, V Lo, TKY AT&T Bell Labs Res Florham Park NJ 07932 USA

We present a near-optimal detection method for decoding codes appropriate to transmission using multiple transmit antennas in a fixed wireless environment. The method is a non-trivial generalization of maximum ratio c... 详细信息

ISBN: (纸本)0780351061

关键词： Bandwidth Constellation diagram Decoding Diversity reception Fading modulation coding Receiving antennas Signal processing Transmitters Transmitting antennas

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An improved scheme in CDMA forward link using unequal error protection

An improved scheme in CDMA forward link using unequal error ...

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IEEE International Conference on Universal Personal Communications (ICUPC 98)

作者： Kim, SY Kang, BJ Oh, KN Elect & Telecommun Res Inst Taejon 305606 South Korea

ISBN: (纸本)0780351061

An improved scheme including unequal error protection in CDMA forward link for IMT-2000 is presented. The performance of this scheme is analyzed by the use of a CS-ACELP speech coder, which was proposed primarily for wireless system, and RCPC channel coder over multipath fading channel and BPSK modulation. From the combined analysis results of the bit error sensitivity information on CS-ACELP coder, a quality improvement of 0.4 similar to 1 dB in SEGSNR is achieved. A flexible replacement of the conventional structure without change of the total transmission rate and without puncturing of power control bit can be obtained.

关键词： Binary phase shift keying Error correction codes Fading Information analysis modulation coding Multiaccess communication Performance analysis Power control Speech analysis Wireless sensor networks

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Noncoherent sequence detection of coded linear modulations

Noncoherent sequence detection of coded linear modulations

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IEEE International Conference on Universal Personal Communications (ICUPC 98)

作者： Colavolpe, G Raheli, R Univ Parma Dipartimento Ingn Informaz I-43100 Parma Italy

ISBN: (纸本)0780351061

In this paper, new noncoherent sequence detection algorithms for combined demodulation and decoding of coded amplitude/phase modulations transmitted over additive white Gaussian noise (AWGN) channels are presented. Optimal noncoherent sequence detection requires a tree search and a complexity exponentially increasing with the duration of the transmission. In order to realize simple suboptimal receivers based on the Viterbi algorithm (VA), approximate schemes are proposed, characterized by a performance which approaches that of coherent detection. In the proposed schemes, the tradeoff between complexity and performance is simply controlled by a parameter referred to as implicit phase memory and the number of trellis states. These schemes represent a significant improvement over previous results [I],[a] In a companion paper, noncoherent sequence detection of continuous phase modulations is also proposed [3]. Extensions to the case of linear modulations transmitted through channels affected by intersymbol interference (ISI) are also proposed.

关键词： Additive white noise AWGN Continuous phase modulation Demodulation Envelope detectors modulation coding Phase detection Phase frequency detector Phase modulation Viterbi algorithm

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Study on the characteristics of predictive closed-loop power control algorithms for a cellular DS/CDMA system

Study on the characteristics of predictive closed-loop power...

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IEEE International Conference on Universal Personal Communications (ICUPC 98)

作者： Sim, ML Gunawan, E Soh, CB Soong, BH Univ Telekom Fac Engn Melaka 75450 Malaysia

ISBN: (纸本)0780351061

This paper considers the performance of a reverse link DS/CDMA system with fast closed loop power control algorithms. A predictive power control algorithm is proposed and the performance is compared with the conventional single step-size algorithm. The effects of power control algorithm, power control updating frequency, power control command channel error rate, mobile unit's velocity and increment step size on the system performance are investigated. Lastly, the optimum power control conditions are found and recommended.

关键词： Error correction Error correction codes modulation coding Multiaccess communication Multiple access interference Power control Power system modeling Shadow mapping System performance Transmitters

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Theoretical study of link adaptation algorithms for adaptive modulation in wireless mobile communication systems

Theoretical study of link adaptation algorithms for adaptive...

引用

IEEE International Conference on Universal Personal Communications (ICUPC 98)

作者： Zhao, YP NOKIA GRP Nokia Res Ctr Radio Commun Lab FIN-00045 Helsinki Finland

ISBN: (纸本)0780351061

Adaptive modulation with varying data rate is an attractive scheme to increase the transmission data rate for mobile radio communications. The radio link adaptation (LA) algorithm is an important issue for such a system;however a theoretical analysis of LA algorithms has not previously been carried out. This paper presents a performance analysis of the LA algorithms for slow fading mobile radio channels. The LA algorithms based on the received signal level are studied;the expression of the radio link outage probability and transmission data rate are derived. The simulations were performed in the GSM communication environment, which gave identical results to the theoretical analysis. The results can be used to determine suitable LA algorithms for adaptive modulation under different conditions.

关键词： Algorithm design and analysis Bit error rate GSM Interference Land mobile radio Mobile communication modulation coding Performance analysis Radio link Signal to noise ratio

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