In modern societies, spectrum bands become very expensive and highly requested resources. Many applications based on wireless communications require smart collaboration and wise sharing of available resources. To achieve this goal, concepts of cognitive radio have been recently formulated. Even though, these systems are newly proposed, many researchers are becoming enthusiastically involved in the development of such concepts and implanting them in communication devices. In addition, several recent IEEE wireless communication standards are proposed. Major software environment, framework and cognitive radio concepts are discussed in this manuscript.