The Role of Polarization Diversity for MIMO Systems Under Rayleigh-Fading Environments

IEEE Trans. Antennas Propagat.

et al. 2009

Abstract-MIMO systems where multipath fading is only partially correlated could use polarization diversity to provide a higher diversity gain. Recent letters have proposed the use of tri-polarized antennas and a novel true polarization diversity (TPD) scheme. In this paper, the full potential of TPD is evaluated with both simulations and measurements and compared to conventional orthogonal polarization diversity (OPD). MIMO system performance with respect to capacity and diversity gain is obtained through the use of multimode-stirred chambers for both isotropic and non-isotropic environments. Simulated and measured results in over 591 different MIMO systems show that TPD outperforms conventional OPD for reduced volumes. Likewise, it has been demonstrated that TPD can be effectively combined with spatial diversity to nearly double the diversity gain and MIMO capacity for the same available handset volume.

mentioning

confidence: 99%

Evaluation of True Polarization Diversity for MIMO Systems

Valenzuela-Valdés¹,

Garcı́a-Fernández

IEEE Trans. Antennas Propagat.

et al. 2009

“…The diverse factors affecting diversity gain [1]- [4] and MIMO capacity [5], [6] have been deeply but independently studied in the literature, with the aim of reducing the correlation coefficients between signals. Spatial [7], [8], angular [9], [10], pattern [11] or a combination of these [12] have been reported. In these studies, however, ideal radiation efficiencies are typically employed.…”

mentioning

confidence: 99%

The Influence of Efficiency on Receive Diversity and MIMO Capacity for Rayleigh-Fading Channels

Valenzuela-Valdés¹,

Garcı́a-Fernández

IEEE Trans. Antennas Propagat.

et al. 2008

Abstract-A previously published guideline for MIMO antenna arrays is refuted. The influence of radiation efficiency on diversity gain and MIMO capacity of wireless communications systems is investigated through simulations and measurements using a reverberation chamber. Integrated antennas on a portable device have efficiencies low enough to disallow typical inter-element correlation assumptions. Both diversity gain and MIMO capacity depend on the number of antennas, SNR and efficiency in a complex way. When the efficiency of antennas is considered, certain system capacity losses are predicted and measured. These losses may be recovered through using more receive elements than commonly recommended or through the addition of a smaller number of more efficient antennas.

“…In this way, different correlation coefficients were obtained for the same user-antenna and dipole 1-dipole 2 separating distances. Since a combination of both spatial and true polarization diversity has proven as an effective way to improve diversity in reduced volumes such as the handset [16], two more measurement scenarios were prepared. In scenario III (IV), the distance from a 30 -rotated (90 -rotated) dipole 2 to the phantom was varied in steps.…”

Section: Measurement Setups and Resultsmentioning

confidence: 99%

Effect of User Presence on Receive Diversity and MIMO Capacity for Rayleigh-Fading Channels

Valenzuela-Valdés

Antennas Wirel. Propag. Lett.

Sánchez‐Hernández

2007

Abstract-The effects of the presence of the user on multipleinput-multiple-output (MIMO) performance for wireless communications systems is investigated through measurements in a reverberation chamber. Measured results have demonstrated that despite a decrement on the envelope correlation coefficient, a degradation of both diversity gain and MIMO capacity are expected when the user is present. While the validity of the correlation coefficients for predicting MIMO performance is limited in the presence of the user, the effects have also been found to be strongly dependent upon frequency, antenna topology, and user characteristics.Index Terms-Correlation coefficient, multiple-input-multipleoutput (MIMO) systems, power absorbed.