1,825 research outputs found
Design of a Planar Eleven Antenna for Optimal MIMO Performance as a Wideband Micro Base-station Antenna
A new low-profile planar Eleven antenna is designed for optimal MIMO
performance as a wideband MIMO antenna for micro base-stations in future
wireless communication systems. The design objective has been to optimize both
the reflection coefficient at the input port of the antenna and the 1-bitstream
and 2-bitstream MIMO efficiency of the antenna at the same time, in both the
Rich Isotropic MultiPath (RIMP) and Random Line-of-Sight (Random-LOS)
environments. The planar Eleven antenna can be operated in 2-, 4-, and 8-port
modes with slight modifications. The optimization is performed using genetic
algorithms. The effects of polarization deficiencies and antenna total embedded
efficiency on the MIMO performance of the antenna are further studied. A
prototype of the antenna has been fabricated and the design has been verified
by measurements against the simulations.Comment: 7 pages, 15 figures, 15 reference
Spatial Multiplexing of QPSK Signals with a Single Radio: Antenna Design and Over-the-Air Experiments
The paper describes the implementation and performance analysis of the first
fully-operational beam-space MIMO antenna for the spatial multiplexing of two
QPSK streams. The antenna is composed of a planar three-port radiator with two
varactor diodes terminating the passive ports. Pattern reconfiguration is used
to encode the MIMO information onto orthogonal virtual basis patterns in the
far-field. A measurement campaign was conducted to compare the performance of
the beam-space MIMO system with a conventional 2-by-?2 MIMO system under
realistic propagation conditions. Propagation measurements were conducted for
both systems and the mutual information and symbol error rates were estimated
from Monte-Carlo simulations over the measured channel matrices. The results
show the beam-space MIMO system and the conventional MIMO system exhibit
similar finite-constellation capacity and error performance in NLOS scenarios
when there is sufficient scattering in the channel. In comparison, in LOS
channels, the capacity performance is observed to depend on the relative
polarization of the receiving antennas.Comment: 31 pages, 23 figure
Multi-user Linear Precoding for Multi-polarized Massive MIMO System under Imperfect CSIT
The space limitation and the channel acquisition prevent Massive MIMO from
being easily deployed in a practical setup. Motivated by current deployments of
LTE-Advanced, the use of multi-polarized antennas can be an efficient solution
to address the space constraint. Furthermore, the dual-structured precoding, in
which a preprocessing based on the spatial correlation and a subsequent linear
precoding based on the short-term channel state information at the transmitter
(CSIT) are concatenated, can reduce the feedback overhead efficiently. By
grouping and preprocessing spatially correlated mobile stations (MSs), the
dimension of the precoding signal space is reduced and the corresponding
short-term CSIT dimension is reduced. In this paper, to reduce the feedback
overhead further, we propose a dual-structured multi-user linear precoding, in
which the subgrouping method based on co-polarization is additionally applied
to the spatially grouped MSs in the preprocessing stage. Furthermore, under
imperfect CSIT, the proposed scheme is asymptotically analyzed based on random
matrix theory. By investigating the behavior of the asymptotic performance, we
also propose a new dual-structured precoding in which the precoding mode is
switched between two dual-structured precoding strategies with 1) the
preprocessing based only on the spatial correlation and 2) the preprocessing
based on both the spatial correlation and polarization. Finally, we extend it
to 3D dual-structured precoding.Comment: accepted to IEEE Transactions on Wireless Communication
Dual-Polarized Ricean MIMO Channels: Modeling and Performance Assessment
In wireless communication systems, dual-polarized (DP) instead of
single-polarized (SP) multiple-input multiple-output (MIMO) transmission is
used to improve the spectral efficiency under certain conditions on the channel
and the signal-to-noise ratio (SNR). In order to identify these conditions, we
first propose a novel channel model for DP mobile Ricean MIMO channels for
which statistical channel parameters are readily obtained from a moment-based
channel decomposition. Second, we derive an approximation of the mutual
information (MI), which can be expressed as a function of those statistical
channel parameters. Based on this approximation, we characterize the required
SNR for a DP MIMO system to outperform an SP MIMO system in terms of the MI.
Finally, we apply our results to channel measurements at 2.53 GHz. We find
that, using the proposed channel decomposition and the approximation of the MI,
we are able to reproduce the (practically relevant) SNR values above which DP
MIMO systems outperform SP MIMO systems.Comment: submitted to the IEEE Transactions on Communication
Design of Multi-Antenna System for UMTS Clamshell Mobile Phones with Ground Plane Effects Considerations
In this paper, the influence of the ground plane dimensions on the port-to-port isolation of two closely-spaced Universal Mobile Telecommunications System (UMTS) Planar Inverted-F Antennas (PIFAs) with and without neutralization line is first presented. Parametric studies show the existence of an optimal size of the ground plane allowing optimizing the isolation and the efficiency of the considered antenna-system. The results obtained with this study are used in the second part to develop an efficient neutralized multi-antenna system for clamshell-type mobile phones. The obtained results, in terms of isolation, matching and diversity for the two possible configurations of the clamshell system in use namely the open and the closed states, show that good performance are obtained in the open state and preserved in the closed state. Prototypes of these two configurations are realized and measurement results are in good agreement with the simulations
Correlated shadowing and fading characterization of MIMO off-body channels by means of multiple autonomous on-body nodes
In off-body communication systems low-cost and compact transceivers are important for realistic applications. An autonomous off-body wireless node was designed and integrated onto a textile antenna. Channel measurements were performed for an indoor non line-off-sight 4x2 MIMO (Multiple-Input Multiple-Output) link using four off-body transmitting nodes and two similar fixed receiving nodes. The channel behavior is characterized as Rayleigh fading with lognormal shadowing and is fitted to a model determining fading and shadowing correlation matrices. The physics of the propagation is captured accurately by the model which is further used to simulate a link using diversity by means of Selection Combining, as implemented on the wireless nodes. The performance of measured and simulated links is compared in terms of outage probability level. The measurements and analysis confirm that the correlated shadowing and fading model is relevant for realistic off-body networks employing diversity by means of Selection Combining
- …