應用於直序展頻分碼多工之超寬頻系統的等化性耙式接收器

在無線通信中，信號在時域上的互相干擾 (ISI；ICI) 會妨礙信號的有效傳送。本篇論文描述一種應用於直序展頻分碼多工之超寬頻系統的等化性耙式接收器；在架構上，此接收器使用數種不同形式的等化器；在此系統中，ICI 會明顯地降低系統性能。我們把時間分集的概念應用到所提出的接收器架構上，此接收器有能力收集足夠之經由多路徑抵達接收器的能量，並且藉由耙式接收器結構把這些收到的能量結合起來，如此可以有效地提高訊雜比值。我們模擬此系統而且說明這種接收器在數種通道模型(環境)中的性能，這些環境包括“有直接波的”，“沒有直接波的”，以及“不同發射器與接收器的間隔距離”等各種環境。我們說明了等化性耙式接收器能夠有效地減輕 ICI，所以此接收器的性能優於匹配濾波器型式的耙式接收器以及慣用的等化器，慣用等化器的性能與有兩個分支的等化性耙式接收器的性能相近。此外，在模擬結果中，藉由耙式接收器架構結合能量的能力，我們所提出的接收器都能獲得分集增益。

關鍵字

時間分集；最大比例結合；等化性耙式接收器；線性回授等化器；線性等化器；耙式接收器；後第三代行動通信；直接序列分碼多工；超寬頻；路徑分集；最小均方誤差

並列摘要

Inter-symbol interference (ISI) is one of the main impediments to efficient transmission in wireless communication. This thesis proposes an equalized-RAKE receiver with different types of equalizers for the DS-CDMA based UWB system in which the inter-chip interference (ICI) degrades the system performance significantly. We apply the concepts of time diversity to the proposed receiver which can gather enough multipath energy and effectively increase SNR by RAKE combining. We simulate the system and demonstrate the performance of the proposed receiver in several kinds of channel models (or environments), including LOS, NLOS, and different distances between transmitter and receiver. We show that the equalized-RAKE receiver can effectively mitigate ICI and has a performance better than the matched-filter-type RAKE receiver and the conventional equalizer which has the performance close to that of a 2-finger equalized-RAKE receiver. Besides, the diversity gain is always obtained by RAKE combining in our simulation.

並列關鍵字

time diversity ； Maximum Ratio Combining ； equalized-RAKE receiver ； Linear Feedback Equalizer ； Linear Equalizer ； RAKE receiver ； Beyond 3rd Generation ； Direct-Sequence Code-Division Multiple Access ； Ultra-Wideband ； path diversity ； Minimum Mean-Square Error

參考文獻

[1] S. Haykin, Communication Systems. 4th edition, John Wiley and Sons, 2000.

[2] John G. Proakis, Digital Communications. 4th edition, Irwin/McGraw-Hill, 2000.

[3] Theodore S. Rappaport, Wireless Communications: Principles and Practice. 2nd edition, Prentice Hall PTR, 2002.

[4] Simon R. Saunders, Antennas and Propagation for Wireless Communication Systems. John Wiley & Sons, 1999.

[7] Qinghua Li and Leslie A. Rusch, “Multiuser Detection for DS-CDMA UWB in the Home Environment,” IEEE Journal on Selected Areas in Communications, Vol. 20, No. 9, pp. 1701-1711, Dec. 2002.

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應用於直序展頻分碼多工之超寬頻系統的等化性耙式接收器

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