超寬頻 (UWB) 無線通訊技術的特點為具有極寬的頻帶以及極低的傳輸功率。故可用來提升傳輸速率並且降低和對其他無線通訊系統之間的干擾，而使用脈衝波形調變 (PSM) 技術則可以使傳輸速率更高。它使用數個正交的脈衝 (pulse) 調變資料後，同時傳送訊號，這種平行的傳輸可以讓系統達到高速傳輸的目的，並且使用保護時間 (guard time) 的技術來抑制符距間干擾 (ISI)，使得系統對於多路徑干擾 (multipath interference) 更強健。而PSM 系統的一個主要問題在於多重脈衝之間的干擾 (MPI) 會使系統的效能降低，這會使得系統的容量 (capacity) 受到限制。因此我們使用平行干擾消除技術 (PIC) 來消除脈衝之間的干擾，改善系統的效能。
和傳統直序展頻分碼多工 (DS-CDMA) 技術不同的是，PSM 使用正交的脈衝區分不同的資料，當我們使用 PIC 技術來消除干擾的時候，在重建連續的干擾訊號時，須要很高的取樣頻率，這會使得系統的複雜度大輻度的提昇。因此，我們使用一種特殊的訓練序列 (training sequence) 來估計不同脈衝間的等效基頻干擾，使得接收端的複雜度降低許多。但是當使用者較多或者調變層級較高的時候，必須使用較長的訓練序列才可準確的估計出等效的基頻干擾訊號。
最後，由電腦模擬的結果可以看出在不同的環境中，我們所提出的方法可以有效的提昇系統的效能。我們也將PSM系統和DS-CDMA系統做了效能的比較，我們發現當使用者少的時候，PSM系統比DS-CDMA系統更適合在高傳輸速率的環境中使用。

The significant features of ultra-wideband (UWB) technology are broader spectrum and lower power transmission, which can be applied to increase data rate and reduce interference in wireless communications. In order to meet the demand for high data rate, the pulse shape modulation (PSM) with guard-time technology is applied to UWB system. It uses several orthogonal pulses to modulate the data bits and transmits them at the same time to achieve high data rate and uses the guard-time technique to suppress inter symbol interference (ISI). However, one major problem associated with PSM is that its capacity is seriously limited by multiple-pulse interference (MPI). To overcome this problem, we employ parallel interference cancellation (PIC) technique to deal with the MPI problem for PSM UWB systems.
Unlike CDMA systems, PSM system uses the orthogonal pulses to distinguish different information. It is difficult to reconstruct the continuous signals when we use the PIC technique to cancel the interference. Therefore, we use a special training sequence structure to estimate the equivalent baseband interference between different pulses. That can make the interference reconstruction more easily.
Finally, we show some computer simulation results of the proposed scheme. It shows that the proposed scheme can actually improve the system performance in different situations. We also show some performance comparisons between PSM and DS-CDMA to illustrate that the PSM is more suitable than DS-CDMA in high data rate transmission for UWB systems when the system load is light.

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