| 1. |
- Alayon Glazunov, Andres
(författare)
-
A Monte Carlo study on the diversity measure of a spherical volume
- 2012
-
Ingår i: Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012. - 9781457709180 ; , s. 21-24
-
Konferensbidrag (refereegranskat)abstract
- In this paper we investigate the diversity measure ψ(R h) of MIMO (Multiple-Input Multiple-Output) channels based on the eigenvalues of the full-correlation matrix of the channel matrix R h. We apply this definition to antennas and channels based on the antenna scattering matrix and the spherical vector wave (svw) expansion of the electromagnetic fields. We derive bounds for this diversity measure in an isotropic propagation channel. We further analyze the diversity measure of a spherical volume occupied by decoupled λ/2-dipole antennas by means of Monte Carlo simulations assuming different polarizations, e.g., vertically or horizontally polarizations, 2 orthogonal polarizations and 3 orthogonal polarizations.
|
|
| 2. |
- Alayon Glazunov, Andres
(författare)
-
On the Antenna-Channel Interactions: A Spherical Vector Wave Expansion Approach
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main focus of this thesis is the analysis of the interactions between antennas and channels where electromagnetic fields play a central role. Our goal has been to devise a general framework to enable a clear separation of the properties of the propagation channel from the influence of the antennas at the same time as it provides a common ground for a joint characterization of their properties. For this we have taken help of two tools: 1) a solution to Maxwell's equations, i.e., a spherical vector wave (svw) multi-modal expansion of the electromagnetic field and 2) the scattering matrix representation of an antenna that provides a full description of all its properties as a transmitting, receiving or scattering device. These tools offer a natural characterization of the polarizational, directional, and spatial properties of multiple-input multiple-output (MIMO) antenna systems. In this thesis we first show that under some assumptions the propagation channel and the antenna are equivalent. The equivalence is in the sense that the impact of the channel cross-polarization ratio (XPR) and the antenna effective cross-polarization discrimination (XPD) on the mean effective gain (MEG) of an antenna are symmetrical. We also find bounds on the MEG in a wireless channel. Then we provide closed form expressions for the covariance of the field multi-modes as a function of the Power Angle Spectrum (PAS) and the channel XPR. A new interpretation of the MEG of antennas in terms of field multi-modes is also provided where the maximum MEG is obtained by conjugate mode matching between the antennas and the channel. We also show the (intuitive) result that the optimum decorrelation of the antenna signals is obtained by the excitation of orthogonal spherical vector wave modes. The cross-correlation coefficient between signals at two antenna branches (ports) in the presence of spatially selective interference and additive white gaussian noise is also investigated showing that spatial interference can also be readily modeled in terms of the svw mode expansion. We further devise a correlation model for co- and cross-polarized field components and introduce the concept of mode-to-mode channel mapping, the M-matrix, between the receive and transmit antenna modes. The M-matrix maps the modes excited by the transmitting antenna to the modes exciting the receive antennas and vice versa. The covariance statistics of this M-matrix are expressed as a function of the double-directional power-angular spectrum (PAS) of co- and cross-polarized components of the electromagnetic field. We finally derive physical limitations on the interactions of antennas exciting TM or TE modes (but not both) and wireless propagation channels. Rather than maximizing antenna gain in a single direction we obtain physical limitations on the antenna gain pattern, which is directly translated to more condensed parameters, i.e. the instantaneous effective gain Gi and the mean effective gain Ge if instantaneous realizations or correlation statistics of the expansion coefficients of the electromagnetic field are known, respectively. The obtained limitations are on the maximum of Gi/Q and Ge/Q, which establish a trade-off between link gain and the antenna quality factor Q.
|
|
| 3. |
- Alayon Glazunov, Andres, et al.
(författare)
-
On the mean effective gain expressed in terms of the spherical vector wave expansion of the electromagnetic field
- 2008
-
Konferensbidrag (refereegranskat)abstract
- The mode expansion o®ers a general framework for the analysis of the interaction between antennas andpropagation channels. In this paper, the Mean E®ective Gain (MEG) of an antenna is expressed in termsof the spherical vector wave expansion of the electromagnetic ¯eld. An explicit expression of the MEG isprovided as a function of the normalized average power of modes excited in the propagation channel andthe correlation between the channel modes due to the polarization and spatial selectivity of plane wavesimpinging at the antenna.
|
|
| 4. |
|
|
| 5. |
- Alayon Glazunov, Andres, et al.
(författare)
-
Outdoor-Indoor Channel
- 2012
-
Ingår i: LTE-Advanced and Next Generation Wireless Networks. - Chichester, U.K. : John Wiley & Sons. - 9781119976707 ; , s. 123-151
-
Bokkapitel (refereegranskat)
|
|
| 6. |
- Alayon Glazunov, Andres, et al.
(författare)
-
Physical Modeling of MIMO Antennas and Channels by Means of the Spherical Vector Wave Expansion
- 2009
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper we propose a new physically motivated model that allows to study the interaction between the antennas and the propagation channel for Multiple-Input Multiple-Output (MIMO) systems. The key tools employed in the model are the expansion coefficients of the electromagnetic field in spherical vector waves and the scattering matrix representation of the properties of the antenna. We derive the expansion of the MIMO channel matrix, H, in spherical vector wave modes of the electromagnetic field of the antennas as well as the propagation channel. We also introduce the channel scattering dyadic, C, with a corresponding correlation model for co- and cross-polarized elements and introduce the concept of mode-to-mode channel mapping, the M-matrix, between the receive and transmit antenna modes. The M-matrix maps the modes excited by the transmitting antenna to the modes exciting the receive antennas and vice versa. The covariance statistics of this M-matrix are expressed as a function of the double-directional power-angular spectrum (PAS) of co- and cross-polarized components of the electromagnetic field. Our approach aims at gaining insights into the physics governing the interaction between antennas and channels and it is useful for studying the performance of different antenna designs in a specified propagation channel as well as for modeling the propagation channel. It can furthermore be used to quantify the optimal properties of antennas in a given propagation channel. We illustrate the developed methodology by analyzing the interaction of a 2x2 system of slant polarized half-wavelength dipole antennas with some basic propagation channel models.
|
|
| 7. |
- Alayon Glazunov, Andres, et al.
(författare)
-
Physical modelling of multiple-input multiple-output antennas and channels by means of the spherical vector wave expansion
- 2010
-
Ingår i: IET Microwaves, Antennas & Propagation. - : Institution of Engineering and Technology (IET). - 1751-8725. ; 4:6, s. 778-791
-
Tidskriftsartikel (refereegranskat)abstract
- The authors propose a new physically motivated model that allows the study of the interaction between the antennas and the propagation channel for multiple-input multiple-output (MIMO) systems. The key tools employed in the model are the expansion coefficients of the electromagnetic field in spherical vector waves and the scattering matrix representation of the properties of the antenna. The authors derive the expansion of the MIMO channel matrix, H, in spherical vector wave modes of the electromagnetic field of the antennas as well as the propagation channel. The authors also introduce the channel scattering dyadic, C, with a corresponding correlation model for co-polarised and cross-polarised elements and introduce the concept of mode-to-mode channel mapping, the M-matrix, between the receive and transmit antenna modes. The M-matrix maps the modes excited by the transmitting antenna to the modes exciting the receive antennas and vice versa. The covariance statistics of this M-matrix are expressed as a function of the double-directional power-angular spectrum (PAS) of co-polarised and cross-polarised components of the electromagnetic field. Their approach aims at gaining insights into the physics governing the interaction between antennas and channels and it is useful for studying the performance of different antenna designs in a specified propagation channel as well as for modelling the propagation channel. It can furthermore be used to quantify the optimal properties of antennas in a given propagation channel. The authors illustrate the developed methodology by analysing the interaction of a 2 x 2 system of slant polarised half-wavelength dipole antennas with some basic propagation channel models.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Bernitz, Hedvig, 1970-
(författare)
-
The Swedish Education System and its Challenges in a Multi-Cultural Society
- 2020
-
Ingår i: Freedom of religion. - Oxford : Hart Publishing Ltd. - 9781509935864 - 9781509935871 ; , s. 161-176
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This article aims at discussing and analysing the question of how (and whether) the Swedish school system is equipped to take care of and meet the needs of pupils with other religious beliefs and other traditions thanthose that are regarded as traditionally ‘ Swedish ’. The basis for the discussionis the principle of the best interests of the child, and the right of society to influence pupils to encompass the values of the Swedish community.
|
|
