Research On Synchronization Acquisition Technology Of Spread Spectrum Communication System

Spread spectrum communication technique was originally intended to meet the demands of stronger anti-interference,anti-jamming and confidentiality, which plays an important role in the field of military communications. With the advantage of multiple access communication, distance measuring, satellite navigation and target detection in Civil field, the Spread spectrum communication system have been widely used.As the core technology of spread spectrum communication system, pseudorandom noise(PN) code synchronization capture becomes the key to spread spectrum technology research.It has guiding significance to comprehensive analysis the performance of the PN code capture. Most published literatures which relate to PN code capture, mainly facous on the methods based on threshold judgment which needs to change threshold with noise power 2ns real-tim and exist the problem Capture Performance is sensitive to noise power estimation. the captured performance over the channel under ideal estimation is theoretical derived and verified, the performance sensitivity of 2ns mismatch for the conventional algorithm is analyzed in this paper. In order to solve the problem, using the correlation-peak-position as decision variable, we propose a multi-correlation-peak-position(MCPP) decision algorithm for PN code acquisition without knowledge of 2ns.The MCPP decision algorithm not only enhance the noise robustness,but also avoid the extra overhead of 2ns estimation. It is more suitble for engineering applications.In this paper,the closed-form expressions of detection and false alarm probailities over AWGN channel,Rayleigh channel and Rican channel are provied and simulation verified.Compared with the threshold decision algorithm,The proposed decision algorithm reduces the overhead of the system and improve the acquisition performance.Using FFT to implement the match filter,it can also reduces the complexity of computing.The transmission signal with noise characteristics has the largest differences between each other, which is easy for receiver to decide. The existing binary spreading sequence can only be close to random white noise from the correlation characteristics, however,it can not approach the white noise of the signal from the amplitude distribution.In this paper Gaussian random sequence were studied.The Gaussian random sequences can also approach the white noise of the signal from the amplitude distribution and has better Concealment and anti-intercept properties.In this paper, the MCPP algorithm based on gaussian sequence spread spectrum under the AWGN channel, Rayleigh Channel and Rican channel are also derived and simulation verified. Compared with the m sequence, the results show that the improved MCPP algorithm can guarantee the Concealment and anti-intercept properties better with no loss of capturing performance.