A method of designing two-dimensional complex coefficient FIR digital filters for broadband digital beamforming antennas by a combination of spectral transformation and a window method

Sekiguchi, Takashi; Klouche-Djedid, A.; Karasawa, Yoshio

doi:10.1002/(sici)1520-6440(199803)81:3<22::aid-ecjc3>3.0.co;2-6

Cited by 5 publications

(6 citation statements)

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“…With this closed-form method, 2D FIR trapezoidal filters can be easily designed to instantaneously adapt the operational frequency band and the bandwidth of the CR system as well as to track and enhance temporally broadband-bandpass ST PWs having time-varying DOAs [29]. Compared with previously reported broadband beamforming methods [16,23,28], and also compared with other similar methods, the proposed method achieves the best overall performance for a CR system with respect to instantaneous adaptability, lowest distortion of the desired signal, and highest attenuation of the co-channel interference signals for a given level of computational complexity.…”

Section: Discussionmentioning

confidence: 99%

“…The considered known methods are the DFT beamformer [16], the interpolated delay-and-sum beamformer [23], the frequency-invariant beamformer [28], and the proposed 2D FIR trapezoidal filter-based beamformer. The performances of these beamforming methods have been evaluated using 2D test sequencesx(n x , n t ), synthesized according to (6) in order to simulate spacetime sampled ST PWs associated with the different 1D baseband equivalent temporal intensity functionsb q (t); q = 0, 1, .…”

Section: A Brief Comparison Of Temporally Broadband-bandpass Beamformmentioning

confidence: 99%

“…Both the interpolated delay-and-sum beamformer [23] and the frequency-invariant beamformer [28] may be implemented with the FIR filter structure shown in Fig. 5.…”

Section: A Brief Comparison Of Temporally Broadband-bandpass Beamformmentioning

confidence: 99%

“…Moreover, the design method of the 2D FIR trapezoidal filter is of closed form and takes 0.05 second on average to determine the filter coefficients using the computational resources of a typical personal computer. With the same computational resources, the iterative and complicated design methods proposed for the frequencyinvariant beamformer [28,32,33] take 3-5 seconds on average to determine the beamformer weights.…”

Section: A Brief Comparison Of Temporally Broadband-bandpass Beamformmentioning

confidence: 99%

“…The simulated results shown in Sects. 4 and 5 indicate that, when compared with the previously reported broadband-beamforming methods [16,23,28], the proposed method achieves the best overall performance for a CR system with respect to lowest distortion of the desired signal and highest attenuation of the co-channel interference signals for a given level of computational complexity while achieving instantaneous adaptability in terms of changing frequency band of operation, bandwidth, and the time-varying DOA of the desired signals.…”

Section: An Example Of the Application Of The Proposed Adaptive Beamfmentioning

confidence: 99%

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Adaptive Complex-Coefficient 2D FIR Trapezoidal Filters for Broadband Beamforming in Cognitive Radio Systems

Gunaratne

Bruton

2010

Circuits Syst Signal Process

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A novel design method is proposed for an adaptive discrete-domain beamformer for the beamforming of temporally broadband-bandpass signals in cognitive radio (CR) systems. The method is based on a complex-coefficient 2D finite impulse response (FIR) filter having a trapezoidal-shaped passband. The temporally broadband-bandpass signals are received by a 1D uniformly distributed antenna array (1D UDAA), where the outputs of the antennas are complex-quadrature sampled by the front end of the CR system. This CR system is based on a software defined radio (SDR) architecture and can be instantly reconfigured by the control system to select the appropriate frequency band and the required sampling rate. The subsequent beamforming enhances the spectral components of the desired temporally broadbandbandpass signals by arranging for the asymmetric trapezoidal-shaped passband of the 2D filter transfer function to closely enclose the region of support (ROS) of the spectrum of the desired signal, whereas the ROSs of the spectral components of the interfering signals are enclosed by the stopband. The proposed novel closed-form design method facilitates instant adaptation of the shape and orientation of the passband of the beamforming 2D FIR trapezoidal filter in order to match the time-varying frequency band and the time-varying bandwidth of the signal, as well as to track and enhance received signals with time-varying directions of arrival (DOAs). Simulated results confirm that, compared with previously reported methods, the proposed method achieves the best overall tradeoff with respect to the instantaneous adaptations of the operating frequency band, the bandwidth, and the time-varying DOAs, the distortion of the desired passband signal, and the stopband attenuation of interfering signals.

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Section: Discussionmentioning

confidence: 99%

Section: A Brief Comparison Of Temporally Broadband-bandpass Beamformmentioning

confidence: 99%

“…Both the interpolated delay-and-sum beamformer [23] and the frequency-invariant beamformer [28] may be implemented with the FIR filter structure shown in Fig. 5.…”

Section: A Brief Comparison Of Temporally Broadband-bandpass Beamformmentioning

confidence: 99%

Section: A Brief Comparison Of Temporally Broadband-bandpass Beamformmentioning

confidence: 99%

Section: An Example Of the Application Of The Proposed Adaptive Beamfmentioning

confidence: 99%

See 3 more Smart Citations

Adaptive Complex-Coefficient 2D FIR Trapezoidal Filters for Broadband Beamforming in Cognitive Radio Systems

Gunaratne

Bruton

2010

Circuits Syst Signal Process

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Frequency‐invariant adaptive receiving and transmitting null beamforming*

Sekiguchi

Karasawa

2001

Electron. Comm. Jpn. Pt. I

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SUMMARYFor mobile communication antennas, it is important to form nulls in the radiation pattern so that the antenna does not interfere with other communication systems in transmission. In cases where the frequencies for transmission and reception are different, as in FDD (Frequency Division Duplex) systems, if the weighting in the reception mode is used directly for transmission when forming the radiation pattern adaptively during transmission, the null directions are deviated so that the transmission characteristics are degraded. In this paper, a receiving and transmitting adaptive null beamforming algorithm is proposed in which a digital multibeam forming network for propagating signals with wide fractional bandwidths, having radiation patterns not dependent on the frequency, is used for weight calculation. Since the radiation patterns of multibeams are almost identical at the transmission and reception frequencies, almost identical null depth can be obtained for both transmission and reception after convergence. By means of computer simulation, it is confirmed that the nulls are formed in the incident directions of the interference signals in both transmission and reception and that the null depths are almost identical.

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Wideband beamspace adaptive array utilizing FIR fan filters for multibeam forming

Sekiguchi

Karasawa

2000

IEEE Trans. Signal Process.

105

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A method of designing two-dimensional complex coefficient FIR digital filters for broadband digital beamforming antennas by a combination of spectral transformation and a window method

Cited by 5 publications

References 0 publications

Adaptive Complex-Coefficient 2D FIR Trapezoidal Filters for Broadband Beamforming in Cognitive Radio Systems

Adaptive Complex-Coefficient 2D FIR Trapezoidal Filters for Broadband Beamforming in Cognitive Radio Systems

Frequency‐invariant adaptive receiving and transmitting null beamforming*

Wideband beamspace adaptive array utilizing FIR fan filters for multibeam forming

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