Sensing And Communication Integration Waveform Designing And Signal Processing Based On FMCW

With the advant of the big data era,a good strategy of development and utilization of spectrum resources is very necessary to solve a contradiction between demand for big capacity information service and scarce spectrum resources.On the other hand,With expansion of the battle field and the development of informatization on weapon and equipment,battle field in the future will face a more complex and hostile combat environment.So it need cooperative combat among various arms and multifunctional portable equipments,meaning that an inevitable trend in the future battlefield becomes a comprehensive electronic information fight.In order to solve problem on electromagnetic compatibility among difference systems and scarce spectrum resources,an effective way is to combine multiple systems into one and share spectrum for different services.FMCW has advantages of high resolution on distance and velocity,having become a mainstream waveform for vehicle collision avoidance and UAV obstacle avoidance systems.Meanwhile,it has also good abilities of resolving multipath,anti-doppler and long range transmission under low power,having been widely used in some personal LAN and Internet of things applications.Therefore,researches on the integrated radar communication system based on FMCW have a very good application prospect.In this paper,researches will focus on waveform designing and signal processing of dual function.On one hand,to improve FMCW communication performance,we study on modulation and demodulaton approach of multiple Chirp-rate and multi-carriers FMCW.On the other hand,we use the improved FMCW communication waveform in radar application and discuss the problem on target detection of the communication radar sharing wareform.The contents are summarized as the following:In order to get optimal Chirp-rate set under contradiction of modulation eiffiency and interferce among different Chirp-rate,and to solve the problem of inconsistence at symbol length and bandwidth between different Chirp-rate,multiple Chirp-rate modulation is discussed firstly based on BFT,and the selection on Chirp-rate and impact on doppler are analyzed.On the other hand,a folded Chirp-rate modulation is proposed for the consistence of symbol length and bandwidth,in which Chirp-rate selection is based on maximizing modulation efficiency in the premise of mimizing interference between different Chirp-rates,and optimal incoherent receiver is designed against doppler shift.Finally,test platform is built by USRP and Radio channel simulator,and test results show the feasibility of the algorithm and system's good robustness against doppler.In order to improve modulation eiffiency of multi-carrier and multi-band FMCW system,a FOCDM is proposed by constructing orthogonal wavefrom set in the way of time cycle shift,and the condition of orthogonality and guard interval setting are discussed,then equalizer for multi-path interference is designed.On the other,a multi-band SEFM waveform is designed for modulation eiffiency,which combine with NLFM and multi carriers without frequency overlapping.And SEFM is designed based on minmum of cross interference,owning the time-frequency symmetry construction and the consistency of symbol length and bandwidth.Finally,interference among subbands and guard interval setting are discussed.In order to use Chirp-rate modulation waveform to detect targets,a sharing waveform combined with Chirp-BOK and FSK is designed for dual function.The system performance losses from the change of Chirp-rates and doppler are analyzed,and the relationship between parameters setting and system performance is discussed.On the other hand,influence on multiple symbol coherent accumulation by the change of Chirp-rates is analyed,and a modified accumulation of path is proposed at slow time dimension.Finally,similations shows the feasility of methods in single and multi-target environment.In order to solve doppler spread brought from energy accumulation between intercarriers,and to design radar communication sharing waveform of MIMO FMCW,first part analyzes the cause for doppler spread in multi-band FMCW,and a suppression method is proposed,then carrier the relationship between interval selection and maximum of unambiguous velocity is discussed.In second part,based on multi-band SEFM modulaiton,a MIMO FMCW sharing waveform is designed for minimum cross-correlation and main-toside lobe ratio.Finally,simulations analyze the influence on the target detection performance by communication modulation.