多頻帶正交分頻多工系統於廣義超寬頻通道之效能分析

Performance Analysis of Multiband OFDM Systems over Generic Ultra-Wideband Channels

張睿揚(Jui-Yang Chang)

指導教授 ： 趙啟超

國立清華大學/電機資訊學院/通訊工程研究所/碩士(2008年)

摘要

隨著數位設備的普及，對於低成本與高速度的短距離無線通訊需求已是越來越強烈，而超寬頻正是符合此需求的一項前瞻技術。受益於超寬頻訊號中豐富的頻率分集，超寬頻系統能以極低的功率頻譜密度進行高速傳輸。因為所使用的通道的許多特點，例如 超寬頻帶所帶來的，精細的時域解析度，在接收端解析的通道中所觀察到的路徑群集效應，超寬頻 (Ultra-wideband, UWB) 通訊系統和傳統通訊系統有很大的不同，為了讓通訊系統符合這些特點，目前已提出了一些新的通道模型如802.15.3a與802.15.4a通道模型，這些通道模型是根據所量測到的電磁訊號去定義出來的。通道的特點使得超寬頻通道上的系統效能分析也與過往的問題不同，我們發現一個準確的效能分析必需要考慮超寬頻通道的隨機特性。此外，多頻帶正交分頻多工系統 (Multi-band Orthogonal Frequency Division Multiplexing, MB-OFDM) 已被建議用於超寬頻通訊上，但是在已知的研究中，多頻帶正交分頻多工系統於廣義超寬頻通道的實用分析還嫌欠缺。在本論文中，利用延伸密度函數 (Extended Density Function)，我們首先推導了在廣義超寬頻通道上隨機到來路徑的平均效應，然後我們計算出在實際系統假設下多頻帶正交分頻多工系統的確切訊號干擾雜訊比 (Signal-to-Interference-Plus-Noise Ratio, SINR)，並且用電腦模擬驗證了分析的結果。最後，基於所得到的分析結果，我們也做了一些系統參數選擇上的討論。

關鍵字

訊號干擾雜訊比 ； 多頻帶正交分頻多工系統 ； 超寬頻 ； 802.15.3a通道模型 ； 802.15.4a通道模型

並列摘要

Ultra-wideband (UWB) communication systems are quite different from conventional ones due to many of the special characteristics of the underlying channels. New channel models such as IEEE 802.15.3a and IEEE 802.15.4a channel models are proposed to match the special characteristics. The specialities lead to different problems on the performance analysis over UWB channels. In addition, systems such as the multiband orthogonal frequency division multiplexing (MB-OFDM) system have been proposed for UWB communications;
yet practical analysis for the MB-OFDM system over generic UWB channels is still rare in the literature. In this thesis, by the aid of the extended density function, the average effect of the unique random arrivals in generic UWB channels is first derived. An exact signal-to- interference-plus-noise ratio (SINR) analysis of the MB-OFDM system over UWB channels under practical assumptions is then provided. Obtained analytical results are later verified by computer simulations. Finally, some discussions on the selection of system parameters based on the SINR analysis are given.

並列關鍵字

Signal-to-Interference-plus-Noise Ratio, SINR ； Multiband OFDM, MB-OFDM ； Ultra-wideband, UWB ； IEEE 802.15.3a channel model ； IEEE 802.15.4a channel model

參考文獻

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