Beamforming is a signal processing technique that has the ability to direct the main beam toward signal-of-interest and the null toward signal-of-not-interest without moving antenna array. This technique is achieved b...
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ISBN:
(纸本)9781479900916
Beamforming is a signal processing technique that has the ability to direct the main beam toward signal-of-interest and the null toward signal-of-not-interest without moving antenna array. This technique is achieved by using algorithms which change the amplitude and phase of array pattern continuously. This paper presents hybrid algorithm that is a combination of two algorithms, least mean square algorithm and sample matrix inversion algorithm. The hybrid algorithm (least mean square/samplematrixinversion) is applied on an array of dipoles to overcome the shortcomings of existing algorithms for a robust smart antenna system. To focus the main beam toward the desired direction and place the null in the direction of the interference signals, the weights of the inversionmatrix in samplematrixinversion are calculated and these weights will be the initial weights in least mean square algorithm. The merit of this approach solves the convergence speed problem of the least mean square algorithm as well as the computation intensive exists in sample matrix inversion algorithm and decreases the least mean square error. The simulation results indicate the analyses of least mean square, samplematrixinversion and hybrid algorithm performances. These techniques are compared and verified using MATLAB.
Adaptive beamforming algorithms is the kind of smart antenna algorithms that have the ability to direct the main beam toward the desired signal and to place a null in the direction of the interference signal. Those al...
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ISBN:
(纸本)9780989319317
Adaptive beamforming algorithms is the kind of smart antenna algorithms that have the ability to direct the main beam toward the desired signal and to place a null in the direction of the interference signal. Those algorithms achieve the desired direction by adjusting weights "amplitude and phase" of the array pattern. The proposed hybrid algorithm is presented in this paper that combines between two algorithms to improve the performance of them. This is achieved by utilizing merits of two algorithms and avoiding demerits of them. Those two algorithms are least mean square algorithm and sample matrix inversion algorithm. A hybrid algorithm of least mean square and samplematrixinversion (least mean square/samplematrixinversion) is applied on rectangular microstrip antenna to indicate the performance of the three algorithms. The microstrip antenna covers the range between 1700-1950MHz with resonant frequency 1850MHz. This frequency range is used in many applications such as mobile communication in GSM, IS-95 (CDMA), 3G, and 4G. the conventional algorithms and the hybrid algorithm are compared and verified using MATLAB.
Minimum variance beamformers are usually complemented with diagonal loading techniques in order to provide robustness against several impairments such as imprecise knowledge of the steering vector or finite sample siz...
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Minimum variance beamformers are usually complemented with diagonal loading techniques in order to provide robustness against several impairments such as imprecise knowledge of the steering vector or finite sample size effects. This paper concentrates on this last application of diagonal loading techniques, i.e., it is assumed that the steering vector is perfectly known and that diagonal loading is used to alleviate the finite sample size impairments. The analysis herein is asymptotic in the sense that it is assumed that both the number of antennas and the number of samples are high but have the same order of magnitude. Borrowing some results of random matrix theory, the authors first derive a deterministic expression that describes the asymptotic signal-to-noise-plus-interference ratio (SINR) at the output of the diagonally loaded beamformer. Then, making use of the statistical theory of large observations (also known as general statistical analysis or G-analysis), the authors derive an estimator of the optimum loading factor that is consistent when both the number of antennas and the sample size increase without bound at the same rate. Because of that, the estimator has an excellent performance even in situations where the quotient between the number of observations is low relative to the number of elements of the array.
In this paper, an adaptive antenna arrays processing based on samplematrixinversion (SMI) algorithm with a novel training scheme is presented. The training scheme used is known as distributed training scheme [1]. Th...
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ISBN:
(纸本)9781479923199
In this paper, an adaptive antenna arrays processing based on samplematrixinversion (SMI) algorithm with a novel training scheme is presented. The training scheme used is known as distributed training scheme [1]. The scheme uses distributed placement of the training symbols throughout the packet. The channel estimation, along with this particular training scheme, is designed to track intermittent interference. This type of interference arises due to an uncontrolled and unpredictable environment such as that of a license-exempted case. In this work, we show the comparison between the performance of distributed scheme with pre-amble training method and also with some iterative based adaptation algorithms like LMS and CMA. A lower bound theoretical analysis is made to compare its result to the simulation results. Moreover, analytical expression for the excess MSE are derived for both distributed and preamble training schemes. Short blocks scenario for the creation of intermittent interference is created by using a batch Poisson traffic model.
This paper introduces the study on adaptive beamforming algorithm for phased Antennas. a modified orthogonal algorithm was put forward in this paper. The formulas were derived and steps of computation were given. The ...
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ISBN:
(纸本)9781424418794
This paper introduces the study on adaptive beamforming algorithm for phased Antennas. a modified orthogonal algorithm was put forward in this paper. The formulas were derived and steps of computation were given. The new algorithm had less computation than orthogonal algorithm with the similar performance. The theoretical analysis and computer simulation results showed that the algorithm was effective.
Serious ground clutter is of significant influence for target detection in an airship-borne passive bistatic radar (ABPBR) using frequency modulated broadcasting signals. The authors propose a data segment processing ...
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Serious ground clutter is of significant influence for target detection in an airship-borne passive bistatic radar (ABPBR) using frequency modulated broadcasting signals. The authors propose a data segment processing scheme to recover the direct signal from multi-path clutter and suppress the multi-path in the surveillance channel in an ABPBR. Super exponential (SE) equaliser and sample matrix inversion algorithm are exploited to recover the transmitted signal and suppress the serious multi-path interference, respectively. It is shown that the proposed algorithms can accomplish the target detection task effectively by computer simulations.
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