寬頻分碼多重進接智慧型天線接收器之模擬與效能評估

Abstract

為了實現第三代行動通訊系統，使用結合許多先進技術的寬頻分碼多工進接（W-CDMA）是必然的趨勢。在本論文中，吾人利用Simulink軟體套件，建立寬頻分碼多重進接接收器鏈結層部分之模擬平台，其包含循環餘數檢測(CRC)、通道編碼(Channel coding)、交錯(Interleaving)、速率匹配(Rate matching)等，以及犁耙(RAKE)接收器，並且於寬頻分碼多重進接上鏈路接收器使用陣列天線(antenna array)來降低多重進接干擾(MAI)的影響。具體而言，本論文實現的接收器為所謂之空-時犁耙接收器(space-time RAKE receiver)，它結合了犁耙接收器、陣列天線、傳輸功率控制(TPC)等演算法。吾人為求接收器能在行動端快速移動時，以及在有頻率漂移的情況下，能有效的運作，分別導入快速傅利葉轉換和符號延遲的概念，得到一種簡便、有效、快速的估計架構，此種估計架構可有效的強化空-時犁耙接收器的效能。吾人接著討論時序錯誤的問題，並使用碼擷取(code acquisition)的演算法估計粗略的時序。吾人為使頻率漂移不致影響碼擷取的結果，導入符號延遲改良以傳統相關器(correlator)為基礎的碼擷取。由電腦模擬結果顯示，本論文所提及之強化空-時犁耙接收器，能在3GPP規格下之環境有效運作。

To realize the third-generation mobile communication systems, known as International Mobile Telecommunications-2000 (IMT-2000), the wideband DS-CDMA (W-CDMA) scheme incorporating as many recent technology developments as possible is necessary. In the thesis, we use the Simulink software package to build the link level simulation platform for a W-CDMA receiver, which include CRC, channel coding, interleaving, rate matching, and consider the use of antenna array technology for the reduction of multiple access interference (MAI) in the implementation of the W-CDMA uplink receiver. In particular, the array receiver, RAKE reception, and transmit power control (TPC) are combined leading to an uplink space-time (S-T) RAKE receiver. To combat the fast fading and frequency offset, we consider the use of the concept of Fast Fourier Transform and symbol delay, and obtain a simple, efficient and quick estimation method. This method is shown to offer improvement for the space-time RAKE receiver significantly. We also discuss the timing error problem and employ code acquisition algorithms to roughly estimate the initial timing. To combat the frequency offset during the acquisition period, the symbol delay is incorporated to improve the correlator-based code acquisition. The efficacy of the proposed enhanced space-time RAKE receiver is confirmed by numerical results in a simulated environment following the 3GPP specifications.