Adaptive beamforming of ESPAR antenna based on stochastic approximation theory

Shishkov, Blagovest; Ohira, Takashi

doi:10.1109/apmc.2001.985444

Cited by 17 publications

(14 citation statements)

References 4 publications

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“…Here µ is a parameter called step size, whose value is often determined empirically or by trial and error. Also, it is effective for accelerating convergence if the step size is decreased as the iteration proceeds, for example, µ n = µ 0 e −αn [42]. Here µ 0 is the initial step size and α is the step size reduction ratio.…”

Section: Optimization Algorithmmentioning

confidence: 98%

Electronically steerable parasitic array radiator antenna

Ohira

Iigusa

2004

Electron Comm Jpn Pt II

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SUMMARYThe electronically steerable parasitic array radiator antenna consists of one feed radiating element and parasitic radiating elements placed in the near field of the active radiator. A beam is formed due to spatial electromagnetic field coupling among radiating elements. The radiation pattern is electronically controlled by means of the variable capacitance devices (varactors) loading the parasitic elements. Unlike a conventional phased array, only one transmitter and receiver are needed for system configuration. Therefore, adaptive beamforming of low dissipation power and low fabrication cost can be achieved. On the other hand, there is only one output port to observe the signal and the weights can be controlled indirectly via reactors instead of direct control. In addition, due to interelement mutual coupling and the parasitic element being directly connected to the reactive device, the linear adaptive array theory developed to date cannot be applied straightforward. In this paper, the configuration of this antenna, its operating principle and formulation, and its measurement method, control scheme, and applications to signal processing are presented. We describe a mathematical model to simulate the radio frequency behavior of the antenna, the equivalent weight vector used for formulation of the characteristics, the admittance matrix including varactors, the effective element length, the equivalent steering vector method, the method for effectively extending the variable range of the capacitance of the varactor, the reactance circuit to cancel nonlinear distortions, the method for calibration of varactors and radiation pattern by measurement of near field of the radiating element, the learning criteria used to control radiation patterns autonomously in adaptation to the electromagnetic environment, the reactance optimization algorithm, the concept of the reactance domain signal processing and the direction of arrival estimation based on such a process, and diversity reception and spatial correlation.

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Section: Optimization Algorithmmentioning

confidence: 98%

Electronically steerable parasitic array radiator antenna

Ohira

Iigusa

2004

Electron Comm Jpn Pt II

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“…RF signal processing in this section is composed of a phase non-shifting element and a phase shifting element terminated with a variable capacitor. Since the phase nonshifting element and the phase shifting element are electro magnetically coupled, the output of the RF signal processing is a weighted sum of the received signal at each element [8]. At the receiver, special equalization is required to reduce the Inter Channel Interference (ICI) generated.…”

Section: An Rf Signal Processing Based Diversity Receiver For Thementioning

confidence: 99%

“…The number of subcarriers is assumed to be used for data transmission N. The V-BLAST processors performs MIMO decoding and frequency domain equalization, simultaneously. The channel matrices frequency components are given by (8) where ij H is channel matrices for receiver j from transmitter i, and the size of each matrices are (2 + N) x N, hence the matrices size of H are 2(N + 2) x 2N [1].…”

Section: Rf Signal Processing Based Mimo-ofdmmentioning

confidence: 99%

Low complexity of computational cost of RF signal processing based diversity scheme for MIMO-OFDM systems

Astawa

Moegiharto

Zainudin

et al. 2014

2014 2nd International Conference on Information and Communication Technology (ICoICT)

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It is is capable of doubling the capacity without expanding the occupied frequency bandwidth in Radio Frequency (RF) signal processing based diversity scheme for Multi-Input Multi-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems using 2x2 dimension antenna. This technique is great because the additional diversity can be gained when the method of the linear MIMO decomposition is used. The resulting performance trends show a significant increase when it is compared to MIMO-OFDM schemes using conventional antenna for 2x2. But the complexity of computational cost is high, especially for the larger antenna size. For that reason the complexity of computation cost is proposed by applying technology of RF signal processing for MIMO-OFDM. So the technique, called Kalman filter MIMO equalizer is used to reduce low complexity of computational cost. In this technique the reduction of the matrix size of original channel matrix is made into 2x4 of matrix size for the number of sub-carrier. In additional part error correction coding technique is added by using convolution code techniques and viterbi algorithm applied at receiver side. Computer simulation result shows that the proposed scheme gives low complexity of computational cost and gives additional diversity gain. Keyword--RF; MIMO-OFDM; Kalman Filter; MIMO decomposition; diversity gain.I.

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“…Since the performance of open loop BS-MIMO systems is known, the beamforming capabilities of ESPAR antennas [8], trigger the evaluation of such systems in closed loop environments. In particular, the authors in [9] propose a simple but efficient limited feedback technique, which adapts the transmit radiation pattern produced by the ESPAR antenna, according to channel conditions.…”

Section: Introductionmentioning

confidence: 99%

Closed-Loop Beamspace MIMO Systems with Low Hardware Complexity

Barousis

Kanatas

Kalis

et al. 2009

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference

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Multiple input -multiple output (MIMO) systems have drawn remarkable interest in recent years, since they are known to boost the spectral efficiency of wireless communication systems compared to single antenna architectures. However, the implementation cost and circuit complexity of such systems conflicts the guaranteed high performance gain. Recent research efforts focus on the investigation of cheaper and low complexity transceivers, introducing a novel beamspace MIMO (BS-MIMO) architecture. BS-MIMO systems have shown equivalent performance with the corresponding conventional systems, while they have been also evaluated in closed loop environments. In this paper we extend the closed loop BS MIMO approach presenting advanced limited feedback techniques which outperform predecessor feedback schemes.

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Adaptive beamforming of ESPAR antenna based on stochastic approximation theory

Cited by 17 publications

References 4 publications

Electronically steerable parasitic array radiator antenna

Electronically steerable parasitic array radiator antenna

Low complexity of computational cost of RF signal processing based diversity scheme for MIMO-OFDM systems

Closed-Loop Beamspace MIMO Systems with Low Hardware Complexity

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