Research On Low Density Ultra-Wideband Signal Design And Reception Techniques In Unmanned Vehicles

In the military field,the unmanned system is the main force of the new seneration of world offensive and defensive battlefields.and its distinctive informational features will make it to become a new popular type of combat equipment in the future.The unmanned operation of the unmanned system,the complex task and the flexible application in the high-confrontation battlefield environment determine that the unmanned system must have flexible communication performance such as high reliability and low delay.Therefore,its communication theory and technology have to be proposed.With higher requirements,the anti-interception and anti-interference capabilities of communication systems need to be improved.Aiming at the huge demand for communication performance of unmanned system,this paper proposes a construction method of M-ary orthogonal spread spectrum signal suitable for UWB communication,and carries out detailed model derivation and waveform simulation of the proposed signal.Aiming at the spectrum performance of M-ary spread spectrum signal,the detailed power spectrum derivation of M-ary spread spectrum signal is carried out.Comparing with DS-UWB and TH-UWB,the simulations show that the power spectrum of the M-ary spread spectrum signal is close to a flat continuum,which is similar to white noise The discrete lines are obviously smoothed,the peak power spectral density is also significantly reduced,and the spectral characteristics are better than TH-UWB and DS-UWB.Modulation has been significantly improved,which have important application significance for improving the coexistence and the anti-interception performance of the system.For the error performance of M-ary spread spectrum signals,the error performance of AWGN channel,Rayleigh and Nakagami-m fading channels is theoretically deduced The error performance of direct reception in various channels is given.A closed-form solution for the error performance of M-ary orthogonal spread spectrum signals is proposed.And the simulations are carried out on the MATLAB platform.The results show that in AWGN channel,in case of selecting the same spreading code,the proposed M-ary orthogonal spread spectrum signal has better error rate performance than the original single-symbol direct spread spectrum signal.Considering the reception effect of multipath fading channel,the paper introduces two kinds of transmission and reception methods commonly used in multipath fading channels-RAKE receivers and reference transmission systems.At the same time,the error rate derivation and numerical simulation are carried out for the M-ary spread spectrum signal using the two main modes of RAKE reception and the autocorrelation receiver using TR-UWB system for transmission.