| With the rapid development of the PLA Navy,the demand for all-weather real-time information exchange and cooperative situational awareness of future naval combat formations is increasing,so a new wireless communication system on the sea surface is urgently needed,which can realize high-speed,real-time,reliable tactical information exchange between ships,carrier-borne aircraft and unmanned boats.Therefore,based on the characteristics of clutter channel of sea surface communication and the mature technology and experience of wireless communication at home and abroad,a sea surface transmission waveform based on multi-carrier adaptive modulation coding is developed to achieve high-speed and reliable sea surface data transmission.The main research contents and contributions of the thesis include the following three aspects:Firstly,the research status of sea surface communication and multi-carrier modulation technology at home and abroad is systematically summarized.According to the sea clutter channel environment,the functional indexes and performance indexes of the subject are demonstrated in detail.The trend of maritime wireless communication in the future is analyzed,and the OFDM multi-carrier communication system based on adaptive modulation coding is determined.Combined with the mature mobile communication technology on land and the special sea clutter channel conditions in the ocean,the path attenuation,multipath channel fading and Doppler effect among communication nodes are modeled and analyzed in detail,and the communication indicators in the thesis are analyzed and demonstrated.Secondly,according to the characteristics of sea clutter channel and requirements of project indicators,a multi-carrier modulation wireless communication link with adaptive rate control function is designed.The overall design scheme of multi-carrier transmission waveform is presented,including adaptive modulation coding,time-frequency synchronization and digital IF processing.The algorithm design and processing flow of signal processing modules such as channel coding,OFDM modulation,adaptive rate control,time synchronization,frequency synchronization,forming filter,matching filter and multiphase frequency conversion filter are introduced in detail.The floating point simulation of communication link is carried out by using MATLAB simulation software,and the simulation verification of communication signal power spectrum characteristics,time-frequency synchronization performance,noise estimation performance and full-link communication performance is completed.Finally,Implementation on the software radio platform and experimental verification of the waveform are completed.According to the hardware realization platform and waveform realization overall structure,the realization scheme of digital intermediate frequency,time-frequency synchronization and adaptive rate control in transceiver is introduced in detail.The bit error rate,packet loss rate,adaptive rate control and other indicators of the communication waveform are tested in the laboratory environment.The experimental test results meet the expectation of waveform design and meet the requirements of functional and performance indicators.In the thesis,a multi-carrier wireless transmission waveform with adaptive rate control function in sea clutter channel is designed,which improves the communication ability between ships and provides strong support for maritime cooperative warfare. |
