2、认知无线电的核心思想认知无线电（CR）是Mitola博士为提高个人

2. The core idea of <br>cognitive radio Cognitive radio (CR) is a smart radio technology proposed by Dr. Mitola in 1999 to improve the flexibility of personal radio services. He gave the definition of CR: radio equipment and network Intelligently calculate the user's communication needs, so as to provide them with the required resources and services [1]. In 2003, the FCC defined cognitive radio as "a cognitive radio is a radio that can adjust its transmission parameters based on interaction with the environment" [2]. According to the definition of FCC, cognitive radio should have two capabilities: cognitive function and reconfiguration function [3]. Cognitive functions are mainly used in signal processing and learning. The reconfiguration function means that the cognitive radio dynamically adjusts transmission parameters, modulation mode, operating frequency and other parameters without changing the hardware. The definition given by the famous scholar Simon Haykin from the perspective of signal processing: CR is a kind of real-time perception of the surrounding radio environment, through self-learning to adjust its own technical parameters (such as power, frequency, modulation method, etc.) to adapt to changes in the environment to achieve high efficiency An intelligent radio communication system that uses spectrum resources to achieve high-performance communication [4]. <br>Through the above description of the definition of CR, we can summarize the core idea of ​​CR: Cognitive systems use spectrum detection and intelligent adaptive technology to achieve dynamic allocation of spectrum resources to achieve frequency sharing and improve spectrum utilization. The cognitive implementation process of CR mainly includes three aspects: Frequency Detection, Frequency Analysis, and Frequency Decision. The CR system obtains radio environment information in a certain time and space domain in real time, analyzes and identifies the available frequency spectrum in this specific space and time, and then dynamically allocates frequencies to realize intelligent communication. During the communication, the primary user (Primary User, PU) must not be interfered. Once the primary user signal appears, the frequency use right must be handed over in time to switch to other available frequencies for communication.

2. The core idea of cognitive radio<br>Cognitive Radio (CR) is an intelligent radio technology proposed by Dr Mitola in 1999 to increase the flexibility of his personal radio business, and he defines CR: radio equipment and networks can intelligently calculate the user's communication needs, thereby providing them with the resources and services they need. In 2003, the FCC defined cognitive radio as "cognitive radio" as a radio that adjusts its transmission parameters on the basis of interaction with the environment. According to the FCC's definition, cognitive radio should have two abilities: cognitive function and reconfiguration function. Cognitive function is mainly used in signal processing and learning. The reconfiguration function refers to the cognitive radio dynamically adjusting the transmission parameters, modulation mode and operating frequency without changing the hardware part. Simon Haykin, a famous scholar, defines it from the perspective of signal processing: CR is an intelligent radio communication system that can perceive the surrounding radio environment in real time and adjust its own technical parameters (such as power, frequency, modulation, etc.) to adapt to environmental changes through self-learning, so as to achieve efficient use of spectrum resources and high-performance communication.<br>Through the above description of CR definition, we can summarize the core idea of CR: Cognitive system through spectrum detection and intelligent adaptive technology, to achieve the dynamic allocation of spectrum resources, to achieve frequency sharing and improve spectrum utilization. CR's cognitive implementation process includes spectrum detection, spectrum analysis, and spectrum decision. THE CR SYSTEM OBTAINS THE RADIO ENVIRONMENT INFORMATION IN REAL TIME WITHIN A CERTAIN TIME DOMAIN AND AIRSPACE, AND REALIZES INTELLIGENT COMMUNICATION BY ANALYZING AND IDENTIFYING THE AVAILABLE SPECTRUM IN THIS PARTICULAR SPACE-TIME AREA, AND THEN DYNAMICALLY ALLOCATING THE FREQUENCY. Interference with the primary user (Primary User, PU) during communication is not possible, and once the primary user signal appears, the right to use the frequency must be handed over in a timely manner and switched to other available frequencies for communication.

2. The core idea of cognitive radio<br>Cognitive radio (CR) is an intelligent radio technology put forward by Dr. mitola in 1999 to improve the flexibility of personal radio service. He gave the definition of Cr: radio equipment and network can intelligently calculate the user's communication requirements, so as to provide them with the required resources and services [1]. In 2003, the FCC defined cognitive radio as "cognitive radio is a kind of radio that can adjust its transmission parameters based on the interaction with the environment" [2]. According to the definition of FCC, cognitive radio should have two abilities: cognitive function and reconfiguration function [3]. Cognitive function is mainly used in signal processing and learning. Reconfiguration function refers to the dynamic adjustment of transmission parameters, modulation mode, operating frequency and other parameters of cognitive radio without changing the hardware part. The definition given by famous scholar Simon Haykin from the perspective of signal processing: Cr is an intelligent radio communication system that can sense the surrounding radio environment in real time, adjust its technical parameters (such as power, frequency, modulation mode, etc.) to adapt to environmental changes through self-learning, so as to achieve efficient use of spectrum resources and achieve high-performance communication [4].<br>Through the above description of Cr definition, we can summarize the core idea of Cr: cognitive system realizes the dynamic allocation of spectrum resources through spectrum detection and intelligent adaptive technology to achieve the purpose of frequency sharing and improving spectrum utilization. The cognitive process of Cr implementation mainly includes frequency detection, frequency analysis and frequency decision. CR system can acquire real-time radio environment information in a certain time and space domain, identify the available spectrum in this specific time and space through analysis, and then dynamically allocate the frequency to realize intelligent communication. During the communication, the primary user (PU) cannot be interfered. Once the signal of the primary user appears, the frequency use right must be handed over in time to switch to other available frequencies for communication.<br>