Frequency Agile OFDM System for Radio Communication in High Frequency Bands

Abstract

High Frequency (HF) radio communication existed as the primary source of over-the-horizon communication for decades prior to the wide implementation of satellite and cellular networks. Even today, should satellite communication become unavailable, the robust backup of HF vitally supports long distance data transmission without the need of a cellular infrastructure. This capability is of particular importance to naval applications while at sea. Frequency choice, however, becomes critical in supporting reliable HF communication as too high of a frequency will not return to earth and too low of a frequency will result in high absorption rates within the atmosphere. A potential solution to explore is to use Software Defined Radio to implement dynamic frequency assignment at regular intervals based on predictive modeling software. Once the optimal frequency is selected and available bandwidth determined, additional parameters can then be optimized to support high data rate reliable transmissions. To overcome the turbulent atmospheric conditions within the atmosphere as bandwidth is increased, we study implementation of Orthogonal Frequency Division Multiplexing (OFDM) to enable a multichannel approach to support the available bandwidth. The concept of applying cognitive radio as sensors become available is also introduced for future implementation