Over the Air Testing of MIMO Capable Terminals

Publication: ResearchPh.D. thesis

Abstract

This thesis focuses on multi-probe anechoic chamber testing, which is a promising over the air (OTA) testing method to evaluate multiple-input multiple-output (MIMO) capable terminals. With MIMO technology being adopted by new wireless technologies, mobile manufacturers and cellular operators need standard test methods to evaluate MIMO device performance. Due to its capability to reproduce radio multipath environments in a shielded laboratory, the multi-probe anechoic chamber method has attracted great research attention.

This thesis addresses various aspects related to OTA testing of MIMO capable devices, where the focus is on techniques to emulate radio channels in multi-probe setups with a limited number of probes. Several channel emulation techniques are proposed to create realistic 2D and 3D spatial channel models in the thesis. A novel method to calculate probe weights for the prefaded signal synthesis (PFS) technique is proposed to reproduce geometry-based stochastic channel models (GBSMs) in the multi-probe anechoic chamber setup. Plane wave synthesis technique for channel emulation purpose is investigated theoretically and experimentally in the thesis as well.

The required number of probes is a key issue, as it directly determines the test system costs. In the thesis, the relationship between the test zone size in terms of figure of merits e.g. spatial correlation and capacity, and the required number of probes has been investigated in detail. Further investigation demonstrated that the DUT antenna radiation pattern is relevant to test zone size. As an extension to work in the literature limited to emulate Rayleigh fading channels, a technique to emulate Rician channel model, with a specular component of arbitrary impinging angles is proposed. To reduce the test system cost, a probe selection method and a flexible probe configuration concept are proposed. Experimental verifications of the proposed algorithms and measurement uncertainties in practical setups are investigated and results are included in the thesis.
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This thesis focuses on multi-probe anechoic chamber testing, which is a promising over the air (OTA) testing method to evaluate multiple-input multiple-output (MIMO) capable terminals. With MIMO technology being adopted by new wireless technologies, mobile manufacturers and cellular operators need standard test methods to evaluate MIMO device performance. Due to its capability to reproduce radio multipath environments in a shielded laboratory, the multi-probe anechoic chamber method has attracted great research attention.

This thesis addresses various aspects related to OTA testing of MIMO capable devices, where the focus is on techniques to emulate radio channels in multi-probe setups with a limited number of probes. Several channel emulation techniques are proposed to create realistic 2D and 3D spatial channel models in the thesis. A novel method to calculate probe weights for the prefaded signal synthesis (PFS) technique is proposed to reproduce geometry-based stochastic channel models (GBSMs) in the multi-probe anechoic chamber setup. Plane wave synthesis technique for channel emulation purpose is investigated theoretically and experimentally in the thesis as well.

The required number of probes is a key issue, as it directly determines the test system costs. In the thesis, the relationship between the test zone size in terms of figure of merits e.g. spatial correlation and capacity, and the required number of probes has been investigated in detail. Further investigation demonstrated that the DUT antenna radiation pattern is relevant to test zone size. As an extension to work in the literature limited to emulate Rayleigh fading channels, a technique to emulate Rician channel model, with a specular component of arbitrary impinging angles is proposed. To reduce the test system cost, a probe selection method and a flexible probe configuration concept are proposed. Experimental verifications of the proposed algorithms and measurement uncertainties in practical setups are investigated and results are included in the thesis.
Original languageEnglish
PublisherAalborg University
Number of pages143
StatePublished - 21 Oct 2014

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