本論文之研究目的，在於利用射線彈跳法去模擬，求得超頻寬通訊在五種不同屋頂和兩種不同環境材質的脈衝響應，並在求得脈衝響應後去計算和比較超寬頻通訊的通道特性。 這五種不同屋頂分別為：1.平面屋頂 2.三角形屋頂 3.栱形屋頂 4.金字塔形屋頂 5.折線形屋頂。兩種不同環境材質分別為：1.混凝土2.鐵皮屋。透過這些多路徑通道的脈衝響應，使用二進制的脈波振幅調變(Binary Pulse Amplitude Modulation, BPAM)方法，進而計算超寬頻通訊系統的位元錯誤率(Bit Error Rate,BER)。我們可以從數值結果得知屋頂形狀與環境材質其多路徑對於通訊位元錯誤率性能的影響。 在本篇論文中所比較的通道特性參數，包含有均方根延遲擴散 (RMS delay spread) 、平均超額延遲擴散(mean excess delay spread)、最大的脈衝響應差值小於10dB的個數(NP10dB)與占總能量85%的脈衝個數(NP85)及位元錯誤率。由於無線電波在室內環境中容易受到遮蔽物的影響，這些遮蔽物例如:牆壁、天花板以及傢俱等，使得無線電波經由多重反射、繞射等路徑而到達接收天線，此一現象稱之為多路徑效應(multi-path effect)。由於此效應造成的符際間干擾(InterSymbol Inference,ISI)，使得通訊位元錯誤率及失效率(outage probability)增加，亦即通話品質變差。在這篇論文裡，我們將探討室內的屋頂形狀與環境材質在超寬頻通訊上對位元錯誤率的影響。最後，我們比較這五種不同形狀的屋頂在傳輸率為100MB、訊號與雜訊比(SNR)為20dB下的失效率，並發現到目前這些模擬的形，在金字塔型屋頂有較小的錯誤率且性能明顯的好於其他屋頂形狀。 A comparison of ultra-wideband (UWB) communication characteristics for five different geometrical shapes of roof in the materials of concrete and iron in the same environments are investigated. These five roofs include the flat shape roof, the triangle shape roof, the arched shape roof, the pyramid shape roof, and the mansard shape roof. The impulse responses of these roofs are computed by applying shooting and bouncing ray/image (SBR/Image) techniques and inverse Fourier transform. By using the impulse response of these multi-path channels, the mean excess delay, root mean square (RMS) delay spread, and the number of multi-path arrivals within 10 dB of the peak multi-path arrival (NP10dB), and the number of paths required to meet the 85% energy capture threshold (NP(85%)) for these five roofs could be obtained. Numerical results show that the RMS delay spread for the pyramid shape roof is smaller than those for the other shapes. And the RMS delay spread for the flat shape roof is greater than the other roofs. Finally, the outage probability for binary antipodal-pulse amplitude modulation (B-PAM) system has been calculated.
