Mimo Capacity

The use of conformal antennas in a MIMO link scenario is investigated. Conformal slot antennas are considered both in the transmitter and the receiver. First, a new modified correlation coefficient is derived that goes beyond the Clarke coefficient and takes into account the element radiation pattern. Secondly, a hybrid formulation that accounts for the impact of the mutual coupling and the pattern dependent correlation on the capacity is presented. The mutual coupling for slots placed circumferentially on a paraboloid substrate is derived using a rigorous approach based on Uniform Theory of Diffraction (UTD). The capacity is evaluated for the case of Rayleigh fading channel considering the new pattern dependent correlation coefficient and the conformal antenna mutual coupling. The planar case is included as a limiting case. It is shown that for conformal antennas on a paraboloid the capacity degradation compared to the planar case is up to 0.5 bps/Hz due to coupling and correlation.

Compact Multiple-Input Multiple-Output (MIMO) systems will be a significant improvement for future high-bit-rate wireless applications. Closely spaced antennas however suffer from mutual coupling and highly correlated signals. In order to keep good system performance, the integration of these antennas in small areas needs to be optimized. Recent studies have analyzed a system model that takes into account all the radio chain parameters for basic dipoles. In this paper, a 2x2 MIMO system architecture consisting of coplanar patch antennas will be considered with the objective to find an optimal architecture for different indoor environments.

In this work, the dependence of the capacity of 2xM MIMO systems on the mutual coupling between the transmitting and receiving antennas is investigated taking into account the correlation coefficient given by Clarke's model. Linear arrays of microstrip rectangular antennas are considered both in the transmitting and the receiving ends. The effect of the mutual coupling between microstrip antenna elements on the capacity of the system for several array configurations is studied. Additionally, the impact of non-ideal impedance matching of the antenna elements is investigated. Assuming an infinite array approximation for coupling, it is shown that for element separations more than a half wavelength, coupling has negligible effect on the capacity compared to the uncoupled case. Furthermore, it is shown that the impedance mismatch has a significant effect on capacity. It is also shown that in the case of a 2x2 MIMO system the angle variation of the coupling has a relatively small impact on the capacity.

—A MIMO channel sounder that does not require phase measurements is proposed. The system is based on parasitic antennas, with a single active element connected to a low expensive amplitude only receiver and a proper phase retrieval algorithm whose computation burden is compatible with today personal computers. Numerical simulations confirm the effectiveness of the approach.

In this work, the dependence of the capacity of 2xM MIMO systems on the mutual coupling between the transmitting and receiving antennas is investigated taking into account the correlation coefficient given by Clarke's model. Linear arrays of microstrip rectangular antennas are considered both in the transmitting and the receiving ends. The effect of the mutual coupling between microstrip antenna elements on the capacity of the system for several array configurations is studied. Additionally, the impact of non-ideal impedance matching of the antenna elements is investigated. Assuming an infinite array approximation for coupling, it is shown that for element separations more than a half wavelength, coupling has negligible effect on the capacity compared to the uncoupled case. Furthermore, it is shown that the impedance mismatch has a significant effect on capacity. It is also shown that in the case of a 2x2 MIMO system the angle variation of the coupling has a relatively small impact on the capacity.

The effect of certain non-ideal conditions on spatial diversity is examined. Diversity switches are microwave components that can be found in spatial diversity systems. The effects of the finite isolation are treated along with the effect of mutual coupling between the antenna elements. The mutual coupling is demonstrated for the case of dipoles and rectangular microstrip antennas. Closed form expressions are provided for the correlation efficient of two-branch diversity schemes.

In this work, the dependence of the capacity of 2xM MIMO systems on the mutual coupling between the transmitting and receiving antennas is investigated taking into account the correlation coefficient given by Clarke's model. Linear arrays of microstrip rectangular antennas are considered both in the transmitting and the receiving ends. The effect of the mutual coupling between microstrip antenna elements on the capacity of the system for several array configurations is studied. Additionally, the impact of non-ideal impedance matching of the antenna elements is investigated. Assuming an infinite array approximation for coupling, it is shown that for element separations more than a half wavelength, coupling has negligible effect on the capacity compared to the uncoupled case. Furthermore, it is shown that the impedance mismatch has a significant effect on capacity. It is also shown that in the case of a 2x2 MIMO system the angle variation of the coupling has a relatively small impact on the capacity.

Abstract-  In this paper, a 2x2 and a 4x4 indoor MIMO measurement campaign at a (2 -5) GHz is presented. A statistical analysis to study the effects of a 2x2 and a 4x4 MIMO on the channel capacity with their respective received fixed signal to noise ratios were analyzed both in the LOS
and in NLOS scenarios. Furthermore, investigations were carried out on all the possible wide band antenna polarizations in order to ascertain which mode of propagation yields a highly decorrelated spatial channel. The three received signal to noise ratios namely 10dB, 20dB and 30dB were used to model various received signal powers. It was found that copolar configurations HH and VV yielded the maximum capacity values both in the LOS and in NLOS respectively. Finally, a validity test was conducted and it was realized that the empirical distribution is similar and within the theoretical
(i.i.d) distribution.

In this work, the dependence of the capacity of 2xM MIMO systems on the mutual coupling between the transmitting and receiving antennas is investigated taking into account the correlation coefficient given by Clarke's model. Linear arrays of microstrip rectangular antennas are considered both in the transmitting and the receiving ends. The effect of the mutual coupling between microstrip antenna elements on the capacity of the system for several array configurations is studied. Additionally, the impact of non-ideal impedance matching of the antenna elements is investigated. Assuming an infinite array approximation for coupling, it is shown that for element separations more than a half wavelength, coupling has negligible effect on the capacity compared to the uncoupled case. Furthermore, it is shown that the impedance mismatch has a significant effect on capacity. It is also shown that in the case of a 2x2 MIMO system the angle variation of the coupling has a relatively small impact on the capacity.

The effect of certain non-ideal conditions on spatial diversity is examined. Diversity switches are microwave components that can be found in spatial diversity systems. The effects of the finite isolation are treated along with the effect of mutual coupling between the antenna elements. The mutual coupling is demonstrated for the case of dipoles and rectangular microstrip antennas. Closed form expressions are provided for the correlation efficient of two-branch diversity schemes.