Research Of SNR Estimation And Adaptive Control Based On Cognitive Radio Communication

With the rapid development in wireless communications, wireless service is focusing on those applications which require morebandwidth and higher rates, such as multimedia communication. However, the old spectrum allocation policy result in the spectrumshortage, Cognitive radio, as a new attractive technology, is consedered to be able to resolve the spectrum shortage problem. Cognitive radio can sense its environment and location dynamically, reuse those idle spectrum resources in temporal and spatial domain, and provide frequency bands for new wireless applications. The communication platform based on DSP+FPGA in this paper realizes several kinds of modulation. And the communication platform, cognitive platform and radio frequency platform make up the whole cognitive radio system.Firstly, the paper introduces the development of Cognitive Radio and some key technologies. Secondly, it mainly concerns on the design of communication platform ,including DSP,FPGA,AD9857,AD9235,UART ST16C550 and FLASH AT25F2048N, then,a QPSK SNR estimation algorithms based on DA are studied deeply, including the simulation and FPGA implementation of the algorithms.Finally, further discuss on the adaptive transmission technique is made in this paper, about the realization of adaptive modulation depending on the channel status for data transmitting are introduced.