Baseband Mixed Signal Analysis And Enhanced Separation Algorithm Design

The baseband mixed signal is of great practical value.Having summarized and further improved the current mixed-signal separation theories,the thesis proves the high anti-interception performance and practicability of the baseband mixed signal from the perspectives of mixed-signal recognition,anti-multi-antenna separation,separable domain and separability.The thesis also identifies the design principles of the baseband mixed-signal model and the related modulation parameters.The baseband mixed signal is proved to be equivalent to the single signal passing through the memory channel,based on which the paper obtains the optimal symbol error rate performance boundary of baseband mixed-signal separation by means of maximum likelihood sequence detection.Notably,the equivalent disposal of the baseband signal is a new research method for mixed signals.Based on the above-proven equivalent model,the thesis has proved that all the mixed signals can adopt this method to obtain the optimal symbol error rate performance boundary theoretically and has clarified the potential improvement for the current algorithm.Meanwhile,the thesis also points out that this estimation method has difficulties in calculation and fails to measure the mixed level of mixed signals accurately.In this paper,a new enhanced algorithm is proposed.Without adding extra complexity significantly,this enhanced algorithm highly improves the separation performance,lowers the symbol error floor of the separation algorithm and can improve the performance by 4dB under the condition of high carrier to noise ratio(CNR).The enhanced algorithm also proves the general applicability of this algorithm from both theories and simulation results.This means that the new enhanced algorithm can also be applied to the MCMC algorithm considering the existence of iterative update and partial locking.Baesed on the equivalent model,the thesis proposes the feature J which measures the Inter-symbol interference(ISI)of the mixed signal and defines the carrier to interference plus noise rate(CINR)of the baseband mixed signal.Particularly,J can accurately measure the difficulty in separation of the receiving end and is regarded as a reference standard for performance comparison of current algorithms.Meanwhile,the cooperative receiver can improve the separation performance of the receiving end by changing the parameters of the receiving end and lowering the value of J.Besides,CINR defined by the value of J can measure the actual receiving conditions of the receiving end more accurately.Similarly,CINR can also be used as a reference standard for performance comparison of current algorithms.At the same time,CINR can be adopted to evaluate the noise interference and ISI of the time synchronization of the non-cooperative receiver.Based on the Gadner algorithm,the anti-intercept ability of the baseband mixed signal can be quantitatively measured.