This demonstration presents a wireless powering to a quad-rotor drone. Visitors experience its rotors working even without batteries onboard. The key is a capacitive coupling scheme featuring simple electrodes and electronics. They learn that it is remarkably lightweight since the system employs neither coupling coils nor bulky ferrite cores.

We address the demodulation and decoding of array signals in the presence of fluctuating cochannel interference (CCI). The maximum-likelihood decoder is formulated for the case of N receive antennas and stationary, temporally white Gaussian CCI within blocks of K samples, where KgesN. The pair wise error probability (PEP) is utilized to quantify the degradation in performance resulting from the absence of side information about the CCI. For pairs of code words that differ over a large number of blocks, an asymptotic PEP performance degradation of 10log10(K/(K-N)) decibels is found. An iterative maximization of the log-likelihood function leads to an alternative suboptimal receiver with reduced complexity, including a block-wise adaptive beamforming via a sample matrix inversion (SMI) and a nearest-neighbor decoding. From the statistics of the spatially filtered signals we find the asymptotic PEP performance, and see that the presence of the desired signal, which is known to adversely affect the output of SMI-based beamformers with small sample support, is gradually mitigated in the iterative procedure

The necessary and sufficient condition for constructing a spreading set with decodability is investigated. It is proved that for a given ${\delta}$ -decodable spreading set and a $q \times q$ square matrix $H$ with components $1$ or $-1$ , a ${q\delta}$ -decodable spreading set $S^\ast$ is obtained if and only if $H$ is a Hadamard matrix. In addition, a decoding rule with error correction and message data detection is provided.

A new mathematical model of electronically steerable parasitic array radiator (ESPAR) antennas is proposed. The ESPAR antenna is a kind of adaptive array antenna expected to spread as a terminal antenna for home LANs or wireless ad-hoc networks. Parasitic elements loaded with variable-reactance terminations are excited by mutual-coupling, so the current distributions along each wire element are not in the ideal sinusoidal function. To consider the current distributions, an equivalent weight vector (EWV) model is modified by introducing a vector effective length (VEL) for each wire element. The vector effective length of a parasitic dipole can be calculated by the reactance value of the variable reactor loading the dipole. The directivity of ESPAR antennas can be calculated simply and accurately by the EWV-VEL model.

This paper reports the first experiments on binary reactance diversity. A prototype of a 3-element 5-GHz band ESPAR (electronically steerable parasitic array radiator) antenna is designed and fabricated on a planar printed circuit. It consists of one radiator and two parasitic elements with loading varactor diodes. It functions as a diversity antenna with a diversity scheme that employs a simple binary reactance control, based on the criterion of received power. In an indoor multipath-fading environment, the ESPAR antenna exhibits a diversity performance of 7-dB gain at CDF 99% in spite of its simplified mechanics.

We first consider the problem of decoding a signal from a memoryless SIMO (single-input/multiple-output) channel subject to block-wise stationary cochannel interference (CCI). We employ an iterative expectation-maximization method, arriving at an algorithm which alternately performs a beamforming via a sample matrix inversion and a maximum-likelihood decoding. An analytical analysis of the sample errors after the beamforming provides insight into the procedure. A numerical study shows that with the number of iteration cycles increasing, the sample error squares decrease towards an analytical lower bound, and the error rates at the decoder output improve. Second, the iterative algorithm is employed for the reception of coded OFDM (orthogonal frequency-division multiplexing) signals subject to non-stationary CCI in both the time and frequency dimensions, as typically encountered in decentralized broad-band wireless networks with uncoordinated channel access. Results from computer simulations indicate that the proposed algorithm successfully mitigates the CCI, achieving gains of several decibels over conventional receiver techniques.

We focus on the channel estimation and the decoding of orthogonal frequency-division multiplexing (OFDM) signals in networking scenarios with multipath propagation and strong cochannel interference (CCI). The receiver views the CCI contained in the subchannel signal observations as additional independent Gaussian noise terms with varying variance from subchannel to subchannel as a consequence of the frequency-selectivity of the radio channels. We find that the capacity of OFDM channels with both the gain and the noise variance subject to broad-band fading may significantly exceed the capacity of a comparable OFDM channel with uniform noise power. Linear minimum mean-square error criterion based subchannel gain and noise variance estimators are presented which can exploit this margin, i.e., improve the spectral efficiency. The performance of the estimators is investigated for bit-interleaved coded OFDM systems and Rayleigh fading channels by computer simulations.

The electronically steerable parasitic array radiator (ESPAR) antenna offers low cost and low complexity relative to conventional array antennas. Because of the low complexity of the antenna there is only a single-port output for processing the signals impinging on the antenna elements. Since a reactance-domain MUSIC algorithm for ESPAR antennas has been proposed, the practical problem of estimating the direction of arrival of signals impinging toward an ESPAR antenna can be tackled. In this paper, two experimental methods of estimating the arrival signal angles are proposed. A method of solving the practical problem of calibrating the ESPAR antenna output signal model is also shown. The experimental results show that for one impinging signal the direction of arrival can be estimated with precision of 3 degrees.

In this paper, we present the formulation of the super-exponential blind adaptive beamforming algorithm; which is an extension of the cumulant-based super-exponential blind deconvolution theory presented by Shalvi and Weinstein. Simulation results show the efficacy of the algorithm.

Analog approaches are expected to offer dramatically low power consumption in smart antennas, especially for battery-operated wireless terminal devices. This paper overviews recently developed analog antenna techniques for smart beamforming. Hardware architectures, trained- and blind-control criteria, and adaptation algorithms are introduced along with state-of-the-art devices and a practical experiment.