Research On New Composition Method And Spread Spectrum And Security System Of Orthogonal Matrix

Code Division Multiple Access (CDMA) is one of the key technologies of 3G and 4G communications, a new means of communication system. In this paper, a large number of documents have been searched, and the common spreading sequences in CDMA have been analyzed and discussed. Then, their advantages and disadvantages have been summarized. m sequence has good randomness and correlation, but less code group; Gold sequence is obtained by the m sequence pairs, so it overcomes the shortcomings of m sequence, but losts some adveantages of m sequence, such as run-length features, balance; Walsh sequence has good correlation, but it demands on system synchronization, has less sequence numbers.In this paper, based on the requirements of the CDMA sequence and the existing sequences, the generation method and principle of Similar-orthogonal matrix have been proposed, specifically, the three generation method which are the method based on m sequence, the method based on the exhaustive and the greedy algorithm have been researched. as well as, this paper researched extension methods of Similar-orthogonal matrix, and focused on the simulation and implementation of integrated circuits of the algorithm. Compared with the existing spreading sequences, the number of Similar-orthogonal matrices are more than m sequence and Walsh sequence, and it has better orthogonality. So, the sequences of Similar-orthogonal matrix can be used as the spreading sequences instead of Walsh sequences, the results prove that Similar-orthogonal matrix with good correlation can be used in CDMA systems.Finally, in this paper, the technology of secure communication have been researched, specifically several encryption and decryption methods of the secure communication system have been described. Based on this, the Similar-orthogonal matrix secure communication system is being proposed, the theoretical proof and simulation results have been given, and the feasibility of the system from the results have been analyzed. Then, This paper proposed Similar-orthogonal matrix loop secure communication system, analyzed its feasibility and security. Since, the Similar-orthogonal matrix can be used in digital secure communication. So, digital encryption methods also can been use in the analog voice transmission system, analog signal can be digitized, encrypted and recoveried before transmission. Therefore, this paper analyzed the voice encryption system, then, Similar-orthogonal matrix voice encryption method have been proposed, and simulated. The result proves that the method is a frequency domain encryption, and the system can recover the almost right voice information.