- 學位論文
直接序列展頻傳輸性能分析－以DS-QPSK系統實作模擬
Analysis and simulation of transmission performance based on Direct Sequence Spread Spectrum system
摘要
展頻技術的發展起源於軍事用途，為能在無線通信中達到保密、抗干擾及防竊聽等目的，其原理係將傳送訊號所佔用的頻寬增加，並數倍於傳送資料所需的最小頻寛，讓訊號接近於背景雜訊的功率來作傳輸；本篇報告主要介紹之直接序列展頻系統，係透過一組偽隨機序列產生的展頻碼及相位鍵移處理，使得原來訊號頻寬變大，且單位頻率上的功率變小的技術。 隨著近年行動通訊技術的發展蓬勃及無線網路需求量的與日俱增，各種現代化的通訊工程領域，都與直接序列展頻技術有直接關係，且在面對無線傳輸環境中障礙所造成的多重路徑衰減，由於其使用的展頻碼具自相關的特性，可以達到抑制的效果及較佳的傳輸品質。 本篇報告中運用matlab程式模擬QPSK直接序列展頻系統，並測試訊號在無線通道下的傳輸性能，模擬結果證實其對於干擾訊號及多重訊號衰減的影響，都呈現較佳的效果。
並列摘要
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.
參考文獻
延伸閱讀
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