Studies on the coherence bandwidth of high-frequency vehicular communication system with antenna array

High-frequency (HF) vehicular communication system works with the frequency-selective fading channel, thereby the coherence bandwidth is limited due to the multipath time dispersive effect, which imposes the difficulty for achieving the high-data rate transmission. The present paper investigates the antenna array technique for its ability in reducing the multipath delay spread of the ionosphere channel and, thus, increasing possibly the bandwidth of the HF system. To enable fast moving speed of the vehicular receiver, we propose to use single antenna at the receiver and the adaptive array at the transmitter. The adaptive beamforming is driven based on the protocol design and reciprocity principle of channel. In order to evaluate the performance of array system, a statistical HF double-directional channel model, which includes angular information at both the transmitter and receiver, is presented. The explicit expressions are obtained for calculating the coherence bandwidth. The numerical results show the efficiency of this approach for mid-latitude mid-range channel. Copyright (C) 2009 John Wiley & Sons, Ltd.