Adaptive loading in HF communications

Adaptive bit loading algorithm is an effective way to use spectrum more efficiently when employed by OFDM/SISO systems. In this paper, we apply this algorithm for HF communications adopting OFDM/MIMO scheme with MDAPSK modulations. A MIMO system utilizes multiple antennas at the transmitter and receiver. Such systems have demonstrated the ability to reliably provide high throughput in rich multipath environment. Simulations of OFDM/SISO systems with/without adaptive loading scheme and OFDM/MIMO with adaptive loading scheme are carried out respectively. Results justify the advantage of the combination of an OFDM/MIMO system and the adaptive bit loading algorithm, which leads to significant data rates with improved bit error performance, over traditional HF communications systems.