360-degree azimuth beam scan four-branch MRC adaptive array for secure connected cars

A four-branch maximum ratio combining (MRC) adaptive array arranged in a circular configuration is studied for secure connected car applications. The MRC array has a beam scan capability in the 360° azimuth angle, resulting in a reduced required signal-to-noise power ratio (SNR) to achieve a prescribed signal bit error rate for a quadrature phase shift keying (QPSK) signal, compared with a conventional dipole linear array. It is revealed that the reduction in SNR is caused by two major factors: 1. an increase in the channel gain resulting from an optimum in-phase excitation of the array elements and 2. a decrease in the correlation between the subarrays, which is given by the orthogonal arrangement of the four subarrays with respect to incident waves with a narrow angular power spectrum in both azimuth and elevation, in which forthcoming vehicle-to-vehicle-based connected cars are anticipated to operate.