整合限制選擇型耙式接收器與基因演算法之超寬頻通訊系統多用戶偵測器之實現

Multi-user Detector for DS-UWB System Using Constricted Selection Rake Receiver and Genetic Algorithms

傅瑞翔(Ray-Hsiang Fu)

指導教授 ： 譚旦旭

國立臺北科技大學/電資學院/電機工程系所/碩士(2007年)

摘要

直序式超寬頻通訊（DS-UWB）是目前超寬頻的主要技術之一。超寬頻通訊技術適用於短距離（＜10公尺）環境，其中的多重路徑效應在多用戶情況下，容易影響展頻碼之間的正交特性，進而造成多重存取干擾（Multi-Access Interference, MAI）的問題。為了消除MAI，最佳多用戶偵測器雖然能達到極佳的系統效能，但因計算複雜度太高，故無法實現。為了在效能與複雜度之間取得平衡，若干研究提出了次佳的方法，例如架構於基因演算法的多用戶偵測器（Genetic algorithm based multi-user detector, GA-MUD）。先前的研究提出整合局部接收型耙式接收器（Partial Rake, p-rake）為前級的局部接收型耙式接收器之基因演算法多用戶偵測器（Partial Rake GA-MUD, PRGA-MUD），但其錯誤率依然偏高。因此本研究提出以限制選擇型耙式接收器（Constricted selection rake receiver, cs-rake）為前級的限制選擇型耙式接收器之基因演算法多用戶偵測器（Constricted Selection Rake GA-MUD, CSRGA-MUD），以有效降低位元錯誤率。另外，為了降低運算複雜度，我們進一步提出了一種低複雜度之CSRGA-MUD，藉由犧牲少量BER來降低複雜度，達到複雜度與BER間的平衡。

關鍵字

直序超寬頻 ； 限制選擇型耙式接收器 ； 基因演算法 ； 多用戶偵測器

並列摘要

DS-UWB is one major technology employed in UWB system. However, for the multi-user application the multiple access interference (MAI) due to imperfect orthogonality between spreading codes induced by UWB dense multi-path degrades system performance. Though optimum multi-user detector (OMD) can achieve remarkable performance, its computational complexity is too high to implement. Therefore, many sub-optimal multi-user detectors (MUDs) have been proposed to compromise system performance and complexity, such as the genetic algorithm-based MUD (GA-MUD). Previous work combining the partial rake receiver (p-rake) and GA-MUD has been proposed, but its performance is still not attractive. Therefore, a CSRGA-MUD that combines the constricted selection rake receiver (cs-rake) and GA-MUD is proposed to improve BER performance further. Moreover, for seeking the best trade-off between BER performance and computational complexity, a CSRGA-MUD with lower computational complexity is also proposed.

並列關鍵字

Ultra-Wide Band（UWB） ； Constricted Selection Rake(cs-rake) ； Genetic Algorithm ； Multi-user Detector

參考文獻

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