Wireless Channel Simulator Testbed for Airborne Receivers

In this paper we introduce an air-to-ground channel model extension for a multi-antenna system. The performance of an aeronautical communication system is strongly influenced by the presence of scatterers and by the three-dimensional (3-D) configuration of transmitter and receiver such as location and velocity. Combined statistical and geometrical models were used to offer a time-space description of the channel. Results of two scenarios are presented: an en- route channel and a takeoff/arrival channel. The implemented frequency selective channel simulator allowed to measure the performances in terms of Bit Error Rate (BER) of an aeronautical system when a single carrier modem, using a π/4-DQPSK modulation, has been employed. We show that the spreading of the signal in both time and spatial domain sets a BER floor which is strongly dependent on the scenario analyzed and on the power of the Line-of-Sight path. We further extend the model to a multi antenna system an apply different transmission schemes requiring different channel information at the transmitter side. We observe that the complete knowledge of the channel at the transmitter side and knowledge of the direction of the receiver relative to the transmitter yields in similar performance.