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Massive multiple-input multiple-output (MIMO) is a promising approach for cellular communication due to its energy efficiency and high achievable data rate. These advantages, however, can be realized only when channel state information (CSI) is available at the transmitter. Since there are many antennas, CSI is too large to feed back without compression. To compress CSI, prior work has applied compressive...
A compact planar array with parasitic elements is studied to be used in MIMO systems. Classical compact arrays suffer from high coupling which makes correlation and matching efficiency to be worse. A proper matching network improves these lacks although its bandwidth is low and may increase the antenna size. The proposed antenna makes use of parasitic elements to improve both correlation and efficiency...
A 4-port antenna is designed for evaluating the performance of an MIMO system in indoor environment. Diversity gain, correlation coefficient and channel capacity are calculated and discussed in this paper. The selection diversity becomes more unapparent when using more antennas in MIMO system. Correlation in both rich scattering and high K-factor environment are found below 0.2 and 0.5 respectively...
In this paper, metamaterial spacer based on newly designed SRRs is studied aimed for better bandwidth while satisfying the S-parameters requirement for the MIMO system. The material property is analyzed. The simulations of the design are completed and the results show that the spacer based on such metamaterial can provide a satisfying reduction of the mutual coupling of the antennas over a quite wide...
This paper evaluates the reconfigurability of a 2D fractal tree antenna to improve the capacity of a 2??2 MIMO link using pattern diversity. Each fractal tree antenna possesses several degrees of freedom: number of fractal stages, branches per stage, angle between branches, and parent-to-child branch scaling length. Simulations of various Reconfigurable Printed Fractal Tree Arrays (RPFTAs) are conducted...
In this paper, we investigate a switching scheme involving antenna selection and transmit beamforming modes for a multiple input multiple output (MIMO) system operating over a varying Rician channel. It is shown that that beamforming outperforms antenna selection when line of sight (LOS) component dominates the channel. Also transmit beamforming is superior over antenna selection at high values of...
Limited feedback in multiple antenna wireless systems is a practical technique to obtain channel state information at the transmitter. When the channel is time-varying with memory, however, selected codeword may become outdated before its use at the transmitter. To overcome this problem, we propose a Grassmannian prediction and predictive coding framework for delayed feedback systems by exploiting...
This paper presents field experiments on open-loop precoding multiple input multiple output (MIMO) using a testbed targeting International Mobile Telecommunication - Advanced (IMT-Advanced) systems. Open-loop MIMO is realized by applying Rotational OFDM (R-OFDM) to MIMO transmission. MIMO R-OFDM is more robust with respect to correlated channels than conventional open-loop MIMO-OFDM as was shown by...
Aiming at the special space in the tunnel, this paper assumes the geometric distribution of scatterers which is totally different from on the ground, puts forward a new GBSB model of MIMO channel and deduces the space-time correlation function of the model. The results of theoretical analysis and simulation show that the model can more accurately reflect the factors which impact the channel correlation...
The design of compact diversity antenna for wireless handset applications has been presented. The results obtained demonstrate high potential of such a design for the handset antenna systems realizing various diversity techniques, such as switched diversity, maximal ratio combining and selection diversity. This antenna structure can also be utilized in a MIMO system, where the low mutual coupling...
A method has been introduced to implement the optimum transmission strategy in MIMO systems. Based on the knowledge of the transmitting channel covariance matrix, a de-correlation transform has been designed to remove spatial correlation and antenna mutual coupling in the transmitting antennas. Simulation results show that if there is no correlation in the receiving array, this method can be used...
Aiming at the special space in the tunnel, this paper assumes the geometric distribution of scatterers which is totally different from on the ground, puts forward a new GBSB model of MIMO channel and deduces the space-time correlation function of the model. The results of theoretical analysis and simulation show that the model can more accurately reflect the factors which impact the channel correlation...
A new MIMO channel model based on angular-domain, double-directional channel model is proposed. Angular domain is a more appropriate coordinate to describe the MIMO channel, since the incoming rays and outgoing rays appear in clusters in the real world. This model is developed based on linear space and sampling theory and is applicable to any practical antenna geometry and includes the actual radiation...
The correlation between different fading paths in a MIMO system plays an important role in the reduction of MIMO channel capacity. The correlation is caused by the interaction of statistical distribution of incident waves around a receiver and the pattern of receive antennas. We derive a zero correlation condition matrix to the MIMO system based on the received electric signals. To find how to approach...
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