Research On Anti-interference Detection And Classification Technique In UWB Cognitive Frequency Hopping System

As a typical covert communicatio n method, frequency hopping communication system becomes the primary technical method in tactical communications due to its low probability of being intercepted and detected, fading repelling ability, near- far resistance, and apt to multi- address networking and narrowband system compatibility. However, because of the growing tension of battle spectrum resource and escalating of electronic confrontation, traditional frequency hopping communication technology is unable to fulfill the requirements of rapid and accurate data transmission and is becoming a bottle neck that constraints the development of tactics wireless communication technology. Cognitive radio technology, on the other hand, is a smart radio system, which can interact with and learn from external environment and adjust itself according to the changes of external environment to achieve desired objectives. Therefore, in a complex electromagnetic environment, a combination of adaptive technique based on cognitive radio and traditional frequency hopping communication system is an effective way to enhance the anti- interference ability, to obtain a better communication performance and to overcome the difficulties in a single traditional frequency hopping communication system. Thereby, the spectrum sensor anti- interference techniques of cognitive adaptive frequency hopping system are studied in this topic, a practical scheme of interference detection and classification is given and a possible implementation of ultra wide broadband spectrum receiver is provided. The main work of this paper includes the following aspects:First, the preliminary theories of the existing frequency hopping communication and the principles of frequency hopping communication system is studied, based on that, several key techniques(hopping pattern, fast frequency hopping synchronization, frequency synthesizer, networking capability) of traditional frequency hopping system are analyzed. Then, based on the fact that the existing frequency hopping communication system is unable to meet the complex demands of modern battlefield, the cognitive radio technique is applied to the design of anti- interference frequency hopping system.Secondly, different types of common interference signals for frequency hopping communication system are modeled, analyzed and simulated. An unknown frequency interference detection systematic process is given according to the system requirements. The following algorithms are invo lved in the systematic process: blind detection algorithm of interference, blind id entification algorithm, interference signal parameter extraction algorithm, narrowband and wideband interference signal parameter extraction algorithm based on wavelet singularity detection. And this process was verified via simulation.Finally, several existing designs of wideband data acquisition platforms are compared, including digital down conversion receiver, direct band-pass sampling receiver, wideband digital frequency measuring receiver, guided broadband digital bandwidth matching receiver and wideband digital channelized receiver. Based on FPGA and ADC, a multi-channel ultra wideband spectrum sensor receiver was designed. The data collection of ultra-wideband spectrum is realized, the generation of ultra-wideband spectral data is achieved by using multi-phase digital processing mechanism. The receiver provides a physical platform and data support for the interference signal detection process which mentioned before.