Research On Fast Spectrum Cognitive Technology In Intelligent Multimode Network Communication System

In the emergency communication scenarios of large-scale activities,such as security,rescue and relief,it is necessary to quickly build a wireless multimedia command and monitoring platform within a limited time,and establish an efficient,stable and data transmission network covering the designated area.However,due to the complexity of the scene,it brings great difficulties to the unified management.The wireless network communication system supporting multiple working modes can complete the control of the scene in a short time,and the field commander can understand any area information of the scene in real time through the network.With the rapid development of artificial intelligence and machine learning,it is of great theoretical and practical value to develop multi-mode,multi rate,self-organizing intelligent multi-mode network communication system.In this paper,the intelligent multi-mode network communication system is divided into physical layer,link layer,network layer and application layer.The physical layer is based on digital signal processor,and realizes the monitoring of broadband radio spectrum and the parameter configuration of wireless communication algorithm library on the basis of various hardware drivers.This paper focuses on the research of fast spectrum recognition technology in the physical layer of the system,and demonstrates it from two aspects: the basis of fast spectrum recognition and the key technology of spectrum recognition.The specific contents are: the design of hardware platform of intelligent multi-mode network communication system and the design of width spectrum sensing algorithm.According to the technical specifications and functional requirements of the intelligent multi-mode network communication system,this paper compares and analyzes the hardware implementation technology of the intelligent multi-mode network communication system.Finally,FPGA and AD9361 RF chips are selected as the hardware implementation platform.The hardware circuit board and AD9361 interface program are designed around Xilinx 7 Series FPGA XC7VX690 T.Based on the energy detection method,the 100 MHz ~ 5GHz spectrum is divided into several sub bands,and the whole 4.9GHz spectrum signal is detected by serial scanning.The sub band decision threshold is updated by estimating the noise energy and the wideband spectrum sensing is completed.When the false alarm probability is 0.1 and the SNR is greater than-6dB,the detection probability is greater than 0.8.Finally,the design and verification on the hardware platform of the intelligent multi-mode network communication system can complete the spectrum sensing of 4.9GHz bandwidth signal from 100 MHz to 5GHz twice a second,which can meet the system's requirements for fast spectrum recognition.