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Radar, Sonar and Navigation, IEE Proceedings -

Issue 1 • Date Feb 1998

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Displaying Results 1 - 11 of 11
  • Taxonomy of space-time processing for wireless networks

    Publication Year: 1998 , Page(s): 25 - 31
    Cited by:  Papers (6)  |  Patents (42)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (732 KB)  

    A taxonomy of space-time signal processing is addressed in terms of architectural and algorithmic classification, and the influence of the propagation channel on the space-time processing. The architecture is classified according to link structure, channel reuse and multiple access scheme. Algorithms are classified into channel estimation methods, TDMA and receive algorithms and space-time algorithms. Finally, the effects of Doppler spread, delay spread and angle spread on space-time processing are discussed View full abstract»

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  • Adaptive airborne MTI with tapered antenna arrays

    Publication Year: 1998 , Page(s): 3 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (580 KB)  

    Space-time adaptive processing achieves optimum clutter rejection for airborne radar. Several aspects of space-time adaptive processing in the design phase of an operational system are addressed: use of a realistic array antenna (planar circular, 1204 elements); forward-looking arrangement; comparison with conventional temporal MTI processing; effect of tapering and impact of jamming. Results of this work contribute to the trilateral AMSAR project View full abstract»

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  • Unified channel model for mobile radio systems with smart antennas

    Publication Year: 1998 , Page(s): 32 - 41
    Cited by:  Papers (140)  |  Patents (9)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (864 KB)  

    The definition of flat fading and frequency-selective fading channels is extended to low-rank and high-rank channels to include the angular domain. By physical reasoning a generic channel model is introduced incorporating directions of arrival and a set of parameters is given for its configuration. The time evolution of the scattering processes and directions of arrival is taken into account. Analytical expressions are derived for space-correlation coefficients and frequency-correlation coefficients. Spatial correlation decreases with increasing angular spread and decreasing angle of incidence, measured from a array broadside View full abstract»

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  • Blind channel identification based on cyclic statistics

    Publication Year: 1998 , Page(s): 58 - 62
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    Use of cyclic statistics in fractionally sampled channels in subspace fitting and linear prediction for channel identification is proposed, possibly for multiuser and multiple antennas. Identification schemes are based on cyclic statistics using the stationary multivariate representation, leading to the use of all cyclic statistics. Compared with classical approaches, the methods proposed have an equivalent performance for subspace fitting, and an enhanced performance for linear prediction View full abstract»

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  • Nonlinear nonadaptive space-time processing for airborne early warning radar

    Publication Year: 1998 , Page(s): 9 - 18
    Cited by:  Papers (8)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1020 KB)  

    The paper deals with the cancellation of clutter echoes in modern airborne early warning radar systems equipped with digital beamforming. Performance is compared of the following two-dimensional filters that operate in the angle and Doppler frequency domains: (i) fully adaptive linear filter, (ii) partially adaptive linear filter, (iii) linear filters with displaced phase centre antenna weights and with fixed Chebyshev tapering, and (iv) the nonlinear filter which takes the minimum among the outputs of few linear filters that process the same radar signals with properly selected weights: (i) requires the highest computational burden and a large region of homogeneous clutter to estimate the clutter covariance matrix, (ii) alleviates these drawbacks at the expense of a reduced cancellation, (iii) are the simplest but offer limited performance, (iv) is a compromise solution, since its computational requirement is slightly higher than filter (iii), but much less than (i) and (ii), and its performance is comparable to filters (i) and (ii). Moreover, since it requires a limited form of adaptation, it shows much higher robustness to nonhomogeneous clutter. Further, the filters are compared against live data recorded by the experimental radar adaptive array flight test equipment of NRL. The set of real data, which relates to the sea-to-ground transition, allows demonstration of the robustness of the new nonlinear detector to nonhomogeneous conditions View full abstract»

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  • Space division multiple access (SDMA) field trials. I. Tracking and BER performance

    Publication Year: 1998 , Page(s): 73 - 78
    Cited by:  Papers (10)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (692 KB)  

    An adaptive antenna testbed for mobile communication applications is briefly described and results from field trials presented. The goal is to provide an experimental demonstration of both transmit and receive digital beamforming supporting SDMA user access. Trials are presented for a typical urban environment with different combinations of user positions and the ability of the employed adaptive algorithm to establish the link and track the channels is investigated alongside the link BER performance. The tracking performance of the adaptive algorithm used for SDMA is also tested for an indoor environment against maximum ratio combining and a fixed grid of beams View full abstract»

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  • Space division multiple access (SDMA) field trials. 2. Calibration and linearity issues

    Publication Year: 1998 , Page(s): 79 - 84
    Cited by:  Papers (12)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (568 KB)  

    In Part 1 (see ibid., vol.145, no.1, p.73-8, 1998) an experimental demonstration of both transmit and receive beamforming supporting SDMA user access was given. In Part 2 some implementation issues critical to the performance of an adaptive antenna system are studied from a practical point of view. Results for the sensitivity of the system to calibration errors and the linearity of the transmit power amplifiers are now presented from measurements made during the field trials View full abstract»

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  • Analysis of weight error loss with a multichannel beamformer processor

    Publication Year: 1998 , Page(s): 63 - 72
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (928 KB)  

    An analysis is presented which derives the bit error rate (BER) performance achieved by a multiple-channel coherent BPSK receiver subject to noisy multichannel impulse response (MCIR) estimates. The receiver utilises a frequency-independent beamformer processor prior to coherent detection which is subject to weight error owing to imperfect MCIR estimates. It is demonstrated that in the flat static channel at high SNR the fractional increase in BER compared to the perfect MCIR estimation case is equal to [N-1/2]/LS, where N is the number of antenna elements and LS is the training sequence length. Similar results are derived for the flat Rayleigh-fading case both for total and for zero correlation between the fading at the antenna elements. These results are then extended to consideration of the degradation in receiver sensitivity, termed the weight error loss, which for the Rayleigh-fading channels at high SNR turns out to be independent of both the mean SNR and N, and is inversely proportional to LS View full abstract»

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  • Generalised array manifold model for wireless communication channels with local scattering

    Publication Year: 1998 , Page(s): 51 - 57
    Cited by:  Papers (18)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (712 KB)  

    The authors propose the use of a generalised array manifold for parameterised spatial signature estimation in wireless communication channels with local scattering. The array manifold commonly used for point sources is generalised to include linear combinations of the nominal array response vectors and their derivatives. The motivation behind this idea is to obtain better estimates of the spatial signatures for direction of arrival (DOA) based signal waveform estimation. The estimators proposed exploit the orthogonality between the so-called noise and signal subspaces, leading to a separable solution for the derivative coefficients. As a result, a search is required for the DOAs only. For uniform linear arrays, the spatial signatures are shown to be approximately Vandermonde vectors with damped modes, and a closed-form estimator such as ESPRIT may be used in this case. Simulation examples are included to compare the signal estimation performance obtained using the proposed generalised manifold and the conventional array manifold View full abstract»

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  • Spatio-temporal radio channel characteristics in urban macrocells

    Publication Year: 1998 , Page(s): 42 - 49
    Cited by:  Papers (44)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1520 KB)  

    The performance assessment of new mobile radio base station (BS) transceiver concepts with adaptive intelligent antennas requires realistic directional radio channel models. An appropriate model is derived from the results of an extensive uplink sounding campaign performed at 1.9 GHz in a urban macrocell within the city of Frankfurt. In the experiments the wideband sounder RUSK XL was applied for synthetic aperture reception. The directional multipath propagation is characterised by means of delays, directions of arrival (DOA) at the BS antenna array and mean powers of the multipath components. The coupled delay-DOA-power information is determined by an adaptation of the 2-D unitary ESPRIT algorithm. It can be used directly to configure fading simulators for multiple antenna reception which reflect real-world small-area radio channel properties in simulations at the link level. Additionally, probability distribution functions for excess delays, DOAs and mean powers are derived from the measurement results. They are useful for consideration of directional propagation effects in investigations of the cellular system behaviour View full abstract»

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  • Adaptive cancellation of nonstationary interference in HF antenna arrays

    Publication Year: 1998 , Page(s): 19 - 24
    Cited by:  Papers (13)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (552 KB)  

    The paper statistically analyses and compares temporal variability in the spatial structure of two HF interference signals propagated from known locations via ionospheric channels with different spatial and temporal characteristics. The impact of the particular ionospheric paths propagating HF interference on the cancellation performance of various adaptive beamforming algorithms is investigated using data collected by the receiving antenna array of the Jindalee Facility Alice Springs OTH radar in Alice Springs, Australia. Measurements and analysis statistically confirm that the spatial properties of HF interference signals, and the actual performance improvements gained through the use of adaptive beamforming techniques, are highly dependent on the spatio-temporal characteristics of the prevailing ionospheric circuits linking the particular source location to the receiving array at the selected operating frequency View full abstract»

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Aims & Scope

IEE Proceedings Radar, Sonar and Navigation covers the theory and practice of systems involving the processing of signals for radar, radio location, radio navigation and surveillance purposes.

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