  This paper discusses the need for Cognitive Radio ability in view of the
physical scarcity of wireless spectrum for communication. A background of the
Cognitive Radio technology is presented and the aspect of 'channel state
prediction' is focused upon. Hidden Markov Models (HMM) have been traditionally
used to model the wireless channel behavior but it suffers from certain
limitations. We discuss few techniques of channel state prediction using
machine-learning methods and will extend the Conditional Random Field (CRF)
procedure to this field.
