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—We describe a secure communication scheme that uses the random fluctuation of the natural environment of communication channels. Only the transmitter and the receiver share the communication channel characteristics. From reciprocity between a transmitter and a receiver, it is possible for them to share one-time information of their fluctuating channel.(More)
– 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(More)
Principle, control theory, and application of the ESPAR (Electrically Steerable Parasitic Array Radiator) antenna are introduced. A typical ESPAR antenna consists of monopole or dipole elements, one of which is the radiator (fed element) and the others are the parasitic radiators with variable reactance devices loaded on them. It can provide a lower-cost(More)
—A low-power consumption, small-size smart antenna, named electronically steerable parasitic array radiator (ESPAR), has been designed. Beamforming is achieved by tuning the load reactances at parasitic elements surrounding the active central element. A fast beamforming algorithm based on simultaneous perturbation stochastic approximation with a maximum(More)
The objective of the beamforming with the exploitation of a sensor array is to enhance the signals of the sources from desired directions, suppress the noises and the interfering signals from other directions, and/or simultaneously provide the localization of the associated sources. In this paper, we present a higher order cumulant-based beamforming(More)
—We focus on the channel estimation and the decoding of orthogonal frequency-division multiplexing (OFDM) signals in networking scenarios with multipath propagation and strong co-channel interference (CCI). The receiver views the CCI contained in the subchannel signal observations as additional independent Gaussian noise terms with varying variance from(More)