MIMO-OFDM Joint Radar And Communication Waveform Design Based On Spread Spectrum

With the increasing maturity of technology,radar and communication technologies,as two major applications of electromagnetic theory,have been widely applied in various fields.Whether it is modern military platforms or new intelligent transportation systems in the civilian sector,both require radar equipment and communication devices to perform their respective functions of detection and information transmission.However,excessive redundant electronic devices can result in large platform sizes and severe electromagnetic interference between devices,leading to low system efficiency.To solve this problem,scholars have proposed the design of an integrated system that combines the functions of radar and communication,integrating the communication system and radar system on the same platform using existing technologies.This system can greatly improve the shortage of spectrum resources.The waveform design for radar-communication integration is the core and focus of research in this field.This paper combines spread spectrum technology with MIMO-OFDM technology for waveform design in radar-communication integration.The main research content is summarized as follows:(1)The paper is based on the design and modification of MIMO-OFDM waveform for radar-communication integration.To address the problem of degraded ambiguity function performance of the integrated waveform due to uncertain communication information,which leads to weakened radar detection capability in the radar-communication integrated system,the paper proposes using well-correlated spread spectrum sequences to pre-process random data information and combine them with MIMO-OFDM technology to design a Gold-code spread spectrum-based MIMO-OFDM waveform for radar-communication integration.By combining MIMO-OFDM with spread spectrum sequences and utilizing well-correlated Gold codes for spreading communication information,and then modulating them with OFDM pulse symbols on each antenna,an integrated waveform is obtained that can improve communication rate while enhancing radar performance.Simulation results show that compared to Gold-OFDM and PC-OFDM integrated waveforms under the same simulation conditions,the proposed integrated waveform achieves significantly improved communication rate and reduces sidelobes in the signal’s ambiguity function without compromising communication performance,thereby improving the radar performance of the integrated system.(2)Since m-sequences and Gold sequences are limited in length and generate relatively few sequences,they are susceptible to being cracked,resulting in poor system security.To address this issue,the paper proposes using chaotic sequences with superior non-periodic auto-correlation and cross-correlation properties as the spread spectrum sequences for radar-communication integration waveform.Chaotic sequences have infinite length and a large number of sequences.The cascaded chaotic sequences designed in this paper exhibit better correlation properties compared to single-level chaotic sequences,and thus provide stronger security.Therefore,the weighted and optimized cascaded chaotic sequences are combined with MIMO-OFDM to design the CCDS-MIMO-OFDM waveform for radar-communication integration.The superiority of this integrated waveform is verified through theoretical analysis and simulation.The results show that the sidelobe level of the ambiguity function decreases as the sequence length increases,and the bit error rate also improves accordingly.