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PERFORMANCE ANALYSIS OF A HYBRID CDMA ISMA PROTOCOL FOR INDOOR WIRELESS COMPUTER COMMUNICATIONS

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 1994年第5期12卷 909-916页

作者： VANROOSMALEN, H NIJHOF, J PRASAD, R Faculty of Electrical Engineering Telecommunications and Traffic-Control Systems Group Delft University of Technnology Delft Netherlands

A combination of direct sequence code division multiple access (DS-CDMA) and p-persistent Inhibit Sense multiple access (ISMA) protocols is proposed for Indoor Wireless Communications (IWC). The combination of these two protocols is called the hybrid CDMA/ISMA protocol. The performance of the hybrid CDMA/ISMA protocol is analyzed with a Markov model considering Differential Phase Shift Keying (DPSK) modulation. The performance is measured in terms of throughput and delay. The performance is also evaluated using computer simulation of which the results are in close agreement with the Markov model results. The study of indoor wireless communications using a hybrid CDMA/ISMA protocol can be useful for various applications in research and design offices, medical data communication in hospitals, etc.

关键词： Performance analysis Multiaccess communication access protocols Wireless application protocol Wireless communication direct-sequence code-division multiple access Differential phase shift keying Differential quadrature phase shift keying Phase modulation Throughput

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RAPID-sequence ACQUISITION FOR DS/CDMA SYSTEMS EMPLOYING KASAMI sequenceS

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IEEE TRANSACTIONS ON COMMUNICATIONS 1994年第2-4期42卷 1957-1968页

作者： BARGHOUTHI, RT STUBER, GL School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

A sequence acquisition scheme based on sequential estimation and soft-decision combining methods is proposed and analyzed for direct-sequence CDMA systems employing Kasami sequences. The proposed technique is effective for Kasami sequences having very long periods. The algebraic properties of Kasami sequences are exploited to provide a very reliable estimate of the correct phase of the local shift register before tracking is attempted. This estimate is obtained by generating and combining multiple statistics for each chip that comprises the initial phase estimate. Expressions 'are derived for the mean and variance of the acquisition time, and the probabilities of acquisition, false dismissal, and false alarm. The proposed scheme compares well with the performance of alternative parallel acquisition schemes.

关键词： soft decision shift registers Scheme direct-sequence code-division multiple access sequential estimation tracking False False-positives False alarms acquisition time CDMA mobile communications Variance

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DS-CDMA performance evaluation over measured indoor radio propagation channels

DS-CDMA performance evaluation over measured indoor radio pr...

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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： H. Nikookar R. Prasad Telecominunicntions and Traffic Control Systems Group Intemntionnl Resenrch Center for Telecommunicntions and Radar Delft University of Technnology Delft Netherlands

Performance of direct sequence code division multiple access (DS-CDMA) technique with binary phase shift keying (BPSK) modulation is evaluated over measured data base of 12000 impulse response estimates of indoor channels obtained at two dissimilar office buildings. These indoor channels have lognormal amplitude fading characteristic as well as modified Poison time of arrival of multipath components. Matched filler receiver and average power control are considered. Gold codes are used as spread spectrum codes. Performance is evaluated in terms of average probability of bit error as a function of signal-to-noise ratio. Results can be used in design and assessment of wireless indoor communication systems.

关键词： Multiaccess communication Indoor radio communication Binary phase shift keying direct-sequence code-division multiple access Phase modulation Modulation coding Phase measurement Phase estimation Fading Toxicology

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A modified multi-stage co-channel interference cancellation in asynchronous CDMA systems

A modified multi-stage co-channel interference cancellation ...

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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： E. Sourour M. Nakagawa Department of Electrical Engineering Alexandria University Alexandria Egypt Department of Electrical Engineering Keio University Yokohama Japan

There is increasing interest in direct sequence code division multiple access (DS-CDMA) communication techniques. A modified multi-stage co-channel interference cancellation technique is proposed for asynchronous CDMA. In asynchronous CDMA a desired bit of any user is affected by co-channel interference from two bits from all other users. In the first stage of interference cancellation, by the end of the integration period of a desired bit, each interfering user would have already obtained an estimate for the earliest of its two interfering bits. Hence, the interference contributed by this bit can be rebuilt and subtracted from the conventional matched filter decision statistic of the desired bit. In the second stage, after waiting a period equals to a bit duration, the remaining bits would have been estimated using a first stage cancellation. Their interference can then be rebuilt and canceled. Also the interference that has been canceled in the first stage can be re-canceled using the estimates of the second stage of other users. This system is shown to provide a good performance. It is assumed that the received powers, delays and phases of all users are perfectly attained.

关键词： Interchannel interference Interference cancellation Multiaccess communication Matched filters Delay Statistics direct-sequence code-division multiple access Communication standards Degradation Power control

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A performance analysis of an overlay of CDMA and FDMA satellite communications systems

A performance analysis of an overlay of CDMA and FDMA satell...

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International Conference on Universal Personal Communications

作者： R.M. Stitt J.R. McCarthy M. Rice Defence Communications Research Centre Signal Processing Research Institute University of South Australia Levels SA Australia

The concept of overlay in radio communication systems has been around for some time with particular emphasis on terrestrial links and spectral sharing between spread spectrum and existing narrowband services. We present an analysis regarding a direct sequence code division multiple access (CDMA) and narrowband frequency division multiple access (FDMA) overlay in a satellite environment and discuss models which describe the behaviour of the mutual interference to both systems. Although a CDMA system has an inherent resistance to jamming, an FDMA system with a large number of active users constitutes a severe interference problem for successful operation. Fortunately, a CDMA design affords some flexibility in parameters such as centre frequency, spread rate and power level which can be chosen by the designer in response to different FDMA implementations. We present results for various FDMA frequency allocations within the overlay and discuss the impact of coding and conforming to existing International Telecommunications Union (ITU) regulations.< >

关键词： Performance analysis Multiaccess communication Frequency division multiaccess Satellite broadcasting Narrowband Interference Radio communication Spread spectrum communication direct-sequence code-division multiple access Frequency conversion

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A novel interference rejection scheme for DS-CDMA using adaptive noise cancellation

A novel interference rejection scheme for DS-CDMA using adap...

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International Conference on Communication Systems

作者： S.S.H. Wijayasuriya P.G. Turner G.H. Norton J.P. NcGeehan MTN Networks Sri Lanka Centre for Comunications Research University of Bristol Bristol UK University of Bristol Bristol Bristol GB Centre for Commun. Res. Bristol Univ. UK

This paper proposes a novel solution to the interference cancellation problem in mobile direct sequence code division multiple access (DS-CDMA) systems. Conventional adaptive interference cancellation techniques rely on a training sequence to update the taps of an adaptive filter or decision feedback equaliser (DFE). The strategy proposed in this paper replaces this conventional optimal filtering approach by one based on the principles of adaptive noise cancellation (ANC). As opposed to the conventional optimal filtering approach, the ANC approach exploits the cyclo-stationary properties of the multiple access interference, in order to model the interference generation process. Silent periods (c.f. voice activity factor) can be exploited to derive the interference model. This removes the need for a training sequence and associated system overheads. The scheme employs a conjugate matched filter (CMF) to generate an interference reference input to the adaptive noise canceller. A preliminary investigation of the performance of the proposed scheme is undertaken. The ANC scheme is shown to have a significantly better performance than the conventional receiver and the DFE in the multiple access interference limited environment. It is shown that the scheme can be extended to provide blind interference cancellation in the case of acute near-far conditions.< >

关键词： Multiaccess communication Interference cancellation Decision feedback equalizers Adaptive filters Filtering Noise cancellation multiple access interference direct-sequence code-division multiple access Adaptive systems Adaptive equalizers

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Propagation delay estimation of DS-CDMA signals in a fading environment

Propagation delay estimation of DS-CDMA signals in a fading ...

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1994 IEEE GLOBECOM. Communications: Communications Theory Mini-Conference Record,

作者： E.G. Strom S. Parkvall S.L. Miller B.E. Ottersten Department of Electrical Engineering University of Florida Gainesville FL USA Department of Signals Sensors and Systems Signal Processing Royal Institute of Technology Stockholm Sweden

The problem considered is of estimating propagation delays of the transmitted signals in a direct sequence code division multiple access (DS-CDMA) system operating over fading channels. Special attention is given to the near-far problem. An estimator based on subspace identification techniques is proposed. The Cramer-Rao bound is presented and used as a benchmark when evaluating the performance of the estimator.

关键词： Propagation delay Delay estimation Multiaccess communication Fading Signal processing Sensor systems direct-sequence code-division multiple access Decorrelation Correlators Data communication

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CDMA RAKE receiver for cellular mobile radio in Nakagami fading frequency selective channels

CDMA RAKE receiver for cellular mobile radio in Nakagami fad...

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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： I.M. Salama E.K. Al-Hussaini Electronics and Communications Department Cairo University Giza Egypt

Studies the performance advantage offered by the wideband multipath RAKE structure receiver in a cellular radio direct sequence code division multiple access system (CDMA). The base to mobile link is modeled as a Nakagami fading frequency selective channel. The performance of a RAKE structure receiver employing coherent reception with maximal ratio combining in a frequency selective channel is analyzed and compared with the flat fading case. The degradation in the performance of the receiver as a result of imperfect channel estimation is also studied.

关键词： Fading Multiaccess communication Multipath channels Land mobile radio RAKE receivers Frequency Wideband Land mobile radio cellular systems direct-sequence code-division multiple access Diversity reception

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Implementation of a conjugate matched filter adaptive receiver for DS-CDMA

Implementation of a conjugate matched filter adaptive receiv...

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International Conference on Communication Systems

作者： P.G. Turner S.S.H. Wijayasuriya J.P. McGeehan Centre for Communications Research University of Bristol Bristol UK

The implementation of a conjugate matched filter receiver based on adaptive noise cancellation (CMF-ANC) techniques for asynchronous direct sequence code division multiple access (DS-CDMA) mobile radio is described. The system employs a recursive least squares (RLS) minimisation in the form of a modified QR-decomposition algorithm, which is ideally suited to running on a triangular systolic array. The highly pipelined systolic array has many features which make it attractive for parallel processing architectures and very large scale integration (VLSI). Simulation results are presented for the systolic CMF-ANC receiver performance in the mobile fading environment. It is shown that the QRD-RLS version of the CMF-ANC receiver has a significantly better performance in the multiple access interference limited environment than the conventional linear correlating receiver and out-performs other adaptive strategies not based on noise cancellation techniques, such as the standard RLS algorithm. In addition, the systolic array algorithm offers greater numerical stability than the CMF-ANC receiver employing the conventional RLS adaptive solution and has a much lower computational complexity per processor.< >

关键词： Matched filters Resonance light scattering Systolic arrays Receivers Noise cancellation Very large scale integration direct-sequence code-division multiple access Multiaccess communication Land mobile radio Least squares methods

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Performance of DS-CDMA networks on Rician fading channels with open-loop power control

Performance of DS-CDMA networks on Rician fading channels wi...

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Asilomar Conference on Signals, Systems & Computers

作者： A. Chockalingam L.B. Milstein Department of Electrical and Computer Engineering University of California San Diego CA USA

The paper presents the performance of a direct sequence code division multiple access (DS-CDMA) network: operating over Rician fading channels. The system employs an open-loop power control scheme, in which the power measurements made on the forward link are used on the reverse link to ensure equal average performance for all the users. The system capacity degradation as a function of the open-loop power control error (PCE) is estimated. The PCE is well approximated by a log-normally distributed random variable with standard deviation in the range 1-4 dB. The system performance for channel models with different Rice factors is presented. For applications requiring 10/sup -3/ BER (e.g., voice), with a Rice factor of 6 dB, the capacity degradation compared to perfect power control is found to be less than 4% as long as the standard deviation of PCE (/spl sigma//sub /spl delta//) is less than 1 dB, and increases to 18% when /spl sigma//sub /spl delta// is 2 dB.< >

关键词： Multiaccess communication Rician channels Power control Degradation direct-sequence code-division multiple access Power measurement Error correction Random variables System performance Power system modeling

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