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In distributed antenna system (DAS), delay spreads between the receiver and each transmit antenna are different due to the unequal propagation delays from distributed transmit antennas to mobile receivers. To exploit the merit of DAS, power spreading in distributed transmit antennas is proposed for OFDM-based MIMO systems over frequency-selective fading channel. In this scheme, partial power of the...
In this paper, a L-circularly polarized aperture-coupled feeding microstrip patch antenna array with a high gain and a good axial ratio is presented. It's suitable for operation in portable satellite communications stations. The microstrip line feeding of circular microstrip patch antenna is applied and the coupling aperture is the cross-shaped aperture. The proposed antenna array covers 29.4-31.0...
Utilization of distributed antennas provides an additional dimension for performance enhancement in 4G and beyond cellular networks. Intelligent remote antenna allocation and practical transmission scheme are two most important aspects for the design of DAS. In this study, a sectorized distributed antenna structure is introduced and correspondingly, power adjusted beam switching as a practical transmission...
This paper presents a micromachined patch antenna array with an integrated 2??2 Butler matrix (BM) beamformer. It was designed at 63 GHz and simulated using CST Microwave Studio 3D simulator. The BM is made using a low loss air filled rectangular coaxial line. The structure is constructed by bonding five layers of gold coated photoresist SU-8, each 200 microns thick. The experimental result shows...
In this contribution, an optimal inter-antenna and subblock shifting and inversion (IAS SI) scheme exploiting additional degrees of freedom brought by multiple antennas and subblocks is proposed to alleviate peak-to-average power ratio (PAPR) problem of MIMO-OFDM systems. In order to reduce the complexity of proposed scheme, two suboptimal schemes based on sequential search and transformation are...
A novel pilot design scheme and simple channel estimation algorithm for an orthogonal frequency-division multiplexing (OFDM) system with two transmit antennas is proposed in this paper. The proposed algorithm takes advantage of the essence of SFBC to reduce the interantenna interference. In the proposed channel estimation scheme, the pilot sequences for two transmit antennas are carefully designed...
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