| Summary: | 碩士 === 中原大學 === 電子工程研究所 === 102 === The development of Spread Spectrum technology originated from a military purpose of secrecy, anti-interference, and anti-wiretap in wireless communications. The approach is to increase the bandwidth of signal transmission occupied and double the minimum bandwidth of data transmission needed. The technique makes the power level of signals closer to the background noise to transmit. This thesis focuses on introducing Direct-Sequence Spread Spectrum system (DSSS) that makes an original signal bandwidth larger and the power of a unit of the frequency smaller through a spreading code generated by a series of Pseudo-Noise sequence, and Phase Shift Key (PSK).
With the expansion of mobile communication technology and the growing demand of wireless networks in recent years, various modern communication domains have directly related to the DSSS technique. In the face of multipath fading caused by obstacles in wireless transmission environment, the application of spreading code with autocorrelation characteristic can achieve an effect of control and better transmission qualities.
In the thesis, Using Matlab program to simulate DS-QPSK and test signal transmission performance under a wireless channel. The result verifies that the DS-QPSK presents a great influence upon jamming and multipath fading.
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