Cognitive HF — New perspectives to use the high frequency band

The HF band, located in between 3-30 MHz, can offer single hop communication channels over a very long distances - even up to around the world. Traditionally, the HF is seen primarily as a solution for long communication ranges although it may also be a perfect choice for much shorter communication ranges when high data rates are not a primary target. It is well known that the HF channel is a demanding environment to operate since it changes rapidly, i.e., channel is available at a moment but the next moment it is not. Therefore, a big problem in HF communications is channel access or channel selection. By choosing the used HF channels wisely, i.e., cognitively, the channel behavior and system reliability considerably improves. This paper discusses about a change of paradigm in HF communication that will take place after applying cognitive principles on the HF system.