Rasearch On RF Module Of Cognitive Radio System

Cognitive Radio is a kind of intelligent system of wireless communication. Some of operating parameters will be changed automatically to adapt to the surrounding wireless environment, through the perception and analysis of the environment. The main purpose of the Cognitive Radio is to improve spectrum utilization and ease the strain on the resources of the spectrum.This paper introduces the design of a RF transceiver module applied to Cognitive Radio. The module contained an RF transmitter and an RF receiver, which can complete the spectrum sensing and data communication at the same time. TDD mode was used in the transceiver, which worked at GSM frequency band. The frequency synthesizer was based on the chip Si4133. Direct up conversion model was used in the transmitter, which contained IF amplifier, up converter, filter, power amplifier and so on. The twice-conversion was used in the receiver, which contained low-noise amplifier, downconverter, filter, IF amplifier and so on. The output of the first downconverter was connected to the detection plate, used for the detection and analysis of the frequency spectrum. The second downconverter was followed by an RSSI module to indicate the strength of received signal. At the same time, the IF signal was transmitted to the baseband plate to complete the data receiving. All the work of design and debug of the RF module had been completed. The test results show that the functions of the RF module were realized, including the spectrum detection and the data communication. The parameters of the RF module were achieved the design requirements.