| Multi-waveform tactical radios are used in various fields of communication,of which the radio series of Joint Tactical Radio System(JTRS)are typical representative of multi-waveform radios and have been the major part of digital battlefield.JTRS has a wide range of applications,including many types of waveforms,such as wideband networking waveforms(WNW),anti-interference waveforms,and low-intercept waveforms.Waveform technology is one of the key technologies of JTRS.These waveform technologies can meet many requirements of communication systems.For a tactical radio communication system running a multi-waveforms,the interference problem always exists during the communication process.In order to ensure the reliability of the communication and improve the communication quality and bit error rate performance,the interference problem needs to be solved.The interference of multi-waveform radio stations is mainly shoveled by the frequency hopping mechanism,because the frequency hopping communication has a strong advantage in anti-interference.In addition,since pure communication systems have been unable to meet people’s demands for communication quality and performance,for these systems,in order to improve performance,some other technologies need to be combined,such as channel estimation,synchronization technology,adaptive coding and modulation,and channel decoding.These technologies usually require the key parameter of signal-to-noise ratio,so the research on signal-to-noise ratio estimation algorithms is increasing.This dissertation takes the typical representative of multi-waveform radio station JTRS as an example to study its signal-to-noise ratio estimation and anti-interference technology.The types of waveforms of JTRS include broadband networking waveforms(WNW),anti-interference waveform technology,and so on.The systems include a narrowband single carrier system,a single carrier frequency domain equalization(SC-FDE)system,and an orthogonal frequency division multiplexing(OFDM)system.The narrowband single carrier system and SC-FDE system are the core technologies of anti-interference waveform technology,and the orthogonal frequency division multiplexing system is the core technology of broadband network waveform technology.Firstly,the signal-to-noise ratio estimation algorithms involved in these three systems are studied.Three signal-to-noise ratio estimation algorithms for narrowband single-carrier systems under Gaussian White Noise(AWGN)channels are studied and simulated.The simulation results show that the performance of the second-order fourth-order moment(M2M4)estimation algorithm is the best.Then,the time-domain signal-to-noise ratio estimation algorithm based on the unique word of the SC-FDE system in a multipath fading channel is studied.Simulation results show that the estimation method performs well.Next,the SNR estimation algorithm of OFDM system under Gaussian White Noise(AWGN)channel and multipath fading channel is studied and simulated.The simulation results show that the least square(LS)estimation algorithm has better performance under AWGN channel.In multipath fading channels,the Boumard algorithm and the new SNR estimation algorithm for OFDM systems have different performance advantages under different SNR conditions and different subcarrier conditions.Finally,for the frequency hopping communication system,the principles and common interference patterns of frequency hopping communication are analyzed,the most typical of which is partial frequency band interference.The anti-partial frequency band interference technology in the frequency hopping communication system is studied,a frequency-hopping anti-jamming system based on erasure RS-Turbo cascade and a method for determining the erasure bits of error correction erasure RS codes are proposed.The system can obtain good performance when the partial frequency band interference is not more than 50%. |
