Description

For many people, when they see the term cognitive radio the first thing that comes to mind is the dynamic spectrum sharing (DSS). Indeed, DSS seems to be almost synonymous with cognitive radio in communications and signal processing literature. On the other hand, RF antenna/reconfigurable hardware community treats it as an upgrade of an software-defined radios (SDR's). However, for a neutral observer the term cognitive radio naturally would invoke a notion much more broader than either one of these. In recent years, our attempt has been in developing radios that may conform with such a more general interpretation of what really is, or rather can be, a cognitive radio. Based on essentially what true cognition may mean, we define a type of cognitive radio called a Radiobot as "an intelligent wireless communications device that has the ability to reason and learn from the observed RF environment and past actions to self-decide optimal communications mode and can optimally self-reconfigure its hardware to support the selected mode". Radiobots are expected to be autonomous communication devices that has the capability for self-management and truly cognitive learning and reasoning. Ideally, a Radiobot must be able to observe/sense a wide spectrum band much larger than transmission bandwidth required by its communication mode/modes at any given time. It can self-interpret the sensed wide spectrum to determine the properties of its RF environment and characteristics of RF activity in it. Based on these interpretations and its own communications objectives, the Radiobot can then select the best mode of operation and reconfigure its hardware to indeed achieve that chosen mode of operation. Similar to a cognitive being, it can then learn from experience generated by the success or failure of these actions to make better decisions in future. Clearly, this type of cognitive radio need not simply be aimed at achieving dynamic spectrum allocation as is the focus of almost all current work on cognitive radios. A Radiobot can be an autonomous radio that may enable interoperability and multi-mode operability. It can also be used to achieve either cognitive anti-jamming capabilities or to act as a sophisticated jammer itself. In another scenario, a Radiobot can be a means to achieve advanced LPI/LPD communications.