Improved High Frequency Communications

An investigation of wideband high frequency radio transmissions will be performed when ionospheric skywave propagation, or near vertical incidence skywave propagation, is utilized. The characteristics of the channel will be examined as a function of the operating frequency, polarization, and time of day. The study will be used to develop a multiple-input, multiple-output transmission scheme that increases the data throughput of currently used radios. The waveforms and algorithms will be defined and modeled, and the performance will be predicted. Methods for aggregating bandwidth to achieve high data throughputs will be investigated. The goal is to achieve the information theoretic capacities of the links with new modulation and coding methods. Schemes for adaptive bandwidth allocation will be studied. Methods to provide reliable communication when significant interference and jamming is present will be evaluated. Also, modifications to current relaying schemes in high frequency networks will be studied so that an effective utilization of the high throughput data links can be achieved. A methodology to achieve approval by the International Telecommunications Union and by the Federal Communications Commission will be developed. Preliminary steps will be taken to implement the research in a prototype radio system.