In this paper, a Virtual Drive Test (VDT) emulation methodology for Vehicle to Infrastructure (V2I) Long Term Evolution-Advanced (LTE-A) communications is proposed, evaluated and compared against a traditional drive test approach. A generic antenna and radio test process is developed based on three-dimensional (3D) ray traced channel models, theoretic and measured antenna patterns, Radio Frequency (RF) channel emulation and Hardware In the Loop (HIL) radio measurements. The spatial and temporal multipath components of the radio propagation channel between the Multiple-Input and Multiple-Output (MIMO) enabled LTE-A Base Stations (BS) and the vehicle under test are accurately modeled for a site-specific virtual environment. Measured BS and LTE-A vehicular antenna patterns are incorporated into the system via spatial and polarimetric convolution with the synthetic ray data. The resulting channels are streamed into a wideband channel emulator that connects a multichannel LTE-A BS emulator to a smart-phone representing the vehicular On-Board-Unit (OBU). The laboratory based LTE-A HIL system is used to study the handover process between two serving LTE-A BSs according to the received RF powers at the vehicular OBU. Emulated RF powers and data throughputs are compared with data from a traditional drive test to verify the legitimacy of the proposed methodology. Our VDT results in terms of Reference Signal Received Power (RSRP) and Physical Downlink Shared Channel (PDSCH) throughput match well the real-world LTE-A measurements for Single-Input and Single-Output (SISO) and MIMO operation. This new process benefits from being repeatable and via the use of ray tracing scales to support a wide range of urban and rural operating environments.

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In this paper, a Virtual Drive Testing (VDT) methodology for a MIMO LTE Vehicle to Infrastructure (V2I) urban scenario is proposed and compared with actual road drive tests. We have developed a unique and generic radio performance analysis process based on 3D ray traced channel models, theoretic or measured antenna patterns, RF channel emulation and hardware-in-the-loop radio measurements. A 3D ray-tracing channel model is used to predict the spatial and temporal multipath ray components of the radio propagation channel between an LTE BS and the vehicle. Measured LTE vehicular antenna patterns were then applied using a spatial and polarimetric convolution process. The resulting channels were streamed into a Keysight PropSim F8 channel emulator, which was programmed to communicate with the multi-channel LTE BSs emulator and a Samsung S5 mobile client performing a handover procedure. The VDT emulation method proposed in this paper is shown to be reliable and repeatable and the accuracy of the emulated throughput agreed well with real measurements for MIMO operation.

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