Spatio-Temporal Elliptical Propagation Modeling For Multi-Polarized MIMO
5.2 Validation of the proposed model
5.2 Validation of the proposed model
For analyzing multi-polarized M×N MIMO indoor radio channels, we propose a channel model to simulate its characteristic. The model is based on the Spatio-Temporal Elliptical Propagation model for presenting geometry scheme, Including propagation effect, antenna spacing effect and multipolarized antenna effect, etc, the default values of parameters for simulation are listed in Table 5-1.
Now, we demonstrated the simulation to compare measurement in NLOS and LOS with PA no.1-7 (Fig 5-3).
Table 5-1 Parameter set-up for simulation
Simulation parameter Default value Frequecny [GHz] 5.5 Array spacing (wavelengths) 0.4-2.0
Propagation range(m) 7
Local scatterers numbers 10
Antenna XPD Xa, [dB] 13
SNR [dB] 30
Fig. 5-3 (a) Capacity versus array spacing simulation and measurement (PA no. 1) d=7m (NLOS, LOS )
Fig. 5-3(b) Capacity versus array spacing simulation and measurement (PA no. 2)
Fig 5-3 (c) Capacity versus array spacing simulation and measurement (PA no. 3) d=7m (NLOS, LOS )
Fig. 5-3 (d) Capacity versus array spacing simulation and measurement (PA no. 4)
Fig. 5-3 (e) Capacity versus array spacing simulation and measurement (PA no. 5) Distance=7m (NLOS, LOS )
Fig. 5-3 (f) Capacity versus array spacing simulation and measurement (PA no. 6)
Fig. 5-3(g) Capacity versus array spacing simulation and measurement (PA no. 7) d=7m (NLOS, LOS )
Chapter 6
Conclusion
Effects of array spacing, array multi-polarization, number of array elements, frequency response, bandwidth, and propagation distance on M×N MIMO cahnnel capacity are explored by extended measurement in indoor environments. Six sites and seven polarization arrangements are considered for the measurement. We also have developed a geometrical–based scattering model for multi-polarized MIMO channels, which is validated by the measurement results.
Some phenomena are observed from the measurement results and are summarized as the following:
(1) It seems that the capacity increases as the elements spacing increases, which is due to the increase of de-correlation effect as the spacing increases. This incremental is also increases with the propagation distance or number of array element, which is also due to the increase of de-correlation effect. It is noted that this incremental saturates asymptotically when the array spacing is larger than 0.7 λ or 0.8 λ. It is found that the array spacing has not much effect on the capacity in LOS situation especially when the number of array element is small. However, when the number of array element is
large and the total array length is also large, the overall de-correlation effect due to array spacing is increased and the MIMO capacity is increased. The richness of multipath components in NLOS situations made all phenomena become more obvious.
(2) It is found that polarization mismatch of array elements can increase the capacity.
It is noted this effect may be enhanced by increasing the propagation distances. (3) It is found that mismatch polarization can decrease the saturation length to 0.7 or 0.8 wavelengths. (4) The measurement results show that MIMO capacity frequency response is distributed randomly and changes slightly with propagation range. (5) The local scatterers around Tx/Rx array enhance MIMO capacity.
Appendix
When characterizing the dual-polarized scattering matrix Г0, the different scattering coefficients Гvv , Гhh , Гhv ,and Гvh are calculated using the Fresnel theory and the UTD. For both mechanisms, the scattering coefficient corresponding to a given pair ,(m,n), with m and n standing for h (horizontal) and/or v (vertical) can be written as
Гmn = RxT(m) · S· Tx(m) (A-1)
where Rx(m) and Tx(m) are 3 × one-unit vectors (expressed in a classical Cartesian coordinate system), respectively, representing the Tx and Rx antenna polarizations, i.e.,m and n and , and S is the 3 × 3 dyadic complex coefficient modeling the scattering mechanism (the superscript T is for transposition).
For reflected contributions, S is written as R and is expressed as
where, einc, || erefT
,| and e⊥| and are unit vectors in the directions of the incident/reflected signals parallel and perpendicular to the plane of incidence,
respectively.
ε
r,eff is the complex effective relative permittivity andθ
iincdis theincident angle [40]. Regarding diffraction, S is the UTD dyadic finite-conductive wedge-diffraction coefficient D, the expression of which can be found in [40].
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