The Relationship Between Cognitive Radio And Software Radio
Cognitive radio is an intelligent radio technology that has the capability to independently search and use idle spectrum resources. Cognitive radio technology has provided an effective solution to the contradiction between the growing demand for wireless communication applications and the increasingly tense wireless spectrum resources. At present, cognitive radio technology from theory to practice are facing many difficulties. This paper summarizes the basic principles of cognitive radio, summarizes the key technologies of physical layer, such as radio frequency, spectrum sensing and data transmission, which is related to cognitive radio, and analyzes the future development trend of the technology with the current development prediction.
With the growing demand for wireless communications, wireless communication technology to support the data transmission rate of the increasingly high demand. According to Shannon's information theory, the demand for wireless spectrum resources of these communication systems is correspondingly increasing, which leads to the increasingly tense of spectrum resources suitable for wireless communication, which becomes a new bottleneck restricting the development of wireless communication. On the other hand, the spectrum resources that have been allocated to many existing wireless systems have different degrees of idle time and space. Therefore, it is proposed to use cognitive radio (CR) technology, from the time and space to make full use of those free spectrum resources, so as to effectively solve the above problems.
This idea was fully reflected in the 2003 US Federal Communications Commission (FCC) Notice of Modification of Spectrum Allocation Rules, which explicitly suggests the use of CR technology as a technical means to improve spectrum utilization. Since then, CR technology has been the industry and the academic community of widespread concern, has become a wireless communication research and market development of new hot spots. However, CR technology from theory to large-scale practical application, but also faces many challenges. These challenges include technical, policy and market aspects. This paper summarizes and analyzes the basic principles and key technologies of CR from the technical point of view, and forecasts the future development trend of technology.
In order to understand the basic principles of CR, it is necessary to distinguish CR from software radio (SDR). According to the definition of the Institute of Electronics and Electrical Engineers (IEEE), a radio device can be called SDR is the basic premise: part or all of the baseband or RF signal processing through the use of digital signal processing software to complete; these software can be modified after the factory [5- 11].
Therefore, SDR is concerned with the realization of radio system signal processing; and CR refers to the wireless system can perceive changes in the operating environment, and accordingly adjust the system operating parameters. In this sense, CR is a higher-level concept that includes not only signal processing but also high-level functions of reasoning and planning based on corresponding tasks, policies, rules and objectives.