Evaluation of three-element MIMO access points based on measurements and ray tracing models.

In this paper, the antenna performance for the 5.2 GHz 802.11n network is compared for four different access points with 3 antenna configurations based on the simulated throughput derived from measurements and a ray-tracing model in a two-storey house. The aim here is not only outline a methodology for access point performance that taking account the user equipment orientation, MIMO data streams that can be supported yielding a total throughput metric, but also ascertain the accuracy of the ray tracing model. In order to demonstrate this, two commercial access points are compared with two alternative antenna configurations: an orthogonal array of dipoles and a linear array of vertical dipoles. Radiation patterns, directivity and polarization mix are presented for all access points. Physical layer throughput is computed for all modulation and coding based on the measured spectral responses and simulated channel matrix. Results show the orthogonal dipole array has the best overall performance with the average throughput of 137 Mbps while vertical dipole array works worst with 106 Mbps. The ray tracing model produce results within 8% of differences and more importantly provide the same performance ranking order.