Multiport antenna performance analysis from ray-traced channels for small cells

The evaluation of multi-element antenna (MEA) performance in urban environments is particularly important for the planning and design of reliable, spectrally efficient systems. To date, MIMO communication using large dimensions has not been implemented for commercial systems. But the potential capacity of MIMO is much more significant when the MIMO dimensions become large. The hold-up is not just the shortfall in understanding how to deploy large-dimension MIMO, but also how to design the antenna systems. There is no widely agreed method for evaluating MEAs used by MIMO communications. Even the performance evaluation of a well-established MIMO configuration, such as the small scale systems already used, remains limited. The evaluation often defers to OTA tests in artificial environmental conditions. The real-world performance remains unclear, so care must be taken in design optimization. In this paper, we discuss the incorporation of some physical modeling of the propagation environment to evaluating the MEA performance for a typical urban wireless channel. A ray-optic method is applicable to any 3D environment, and any number of antennas with arbitrary patterns. In this sense it offers a practical approach for large-dimension MIMO evaluation by being able to change the antennas and the environment, all in software. The evaluation method is illustrated by using an MEA slot cube (12 antennas) operating in a specific environment, namely downtown Ottawa.