應用於無線區域網路之互補編碼調變基頻傳收器架構設計

Abstract

隨著通訊技術的不斷進步，新一代無線區域網路的傳輸標準採用 "互補編碼調變"技術，使得原有的傳輸速率從 1Mbps/ 2Mbps 增加 到 5.5 Mbps/ 11Mbps。新的"互補編碼調變"在複雜度上比起既有 的貝克(Barker)碼調變要高出許多。因此在這篇論文中，我們提出 了一個低本、高效能的基頻傳收器架構，可大幅降低系統的複雜度， 使更適合於超大型積體電路的製作。 目前在市面上，如Intersil和CCL，普遍採用的架構為"快速華許轉換式"(FWT)。但是，這不是唯一的解決方式，帶我設計的架構中，我用了"相位差轉換式"(DPT)，做為解調變的理論架構，硬體消耗可以節省90\%以上。相關比較和詳細內容在此論文中會加以詳細討論。 另外就是載波頻率位移的問題，由於傳輸速率的加快，增加了載波頻率位移評估器(AFC)的困難度。因此，我提出了以決策前饋的新架構，而這新架構可以和解調變器緊緊的結合在一起，不僅大幅降低硬體的消耗，在功率方面更可降低97\%以上。

Complementary Code Keying(CCK) is employed as the modulation scheme in IEEE 802.11-1997 and provide 5.5Mbit/s and 11Mbit/s for high data rate transmission. The implementation for the Barker code is very easy, but the complexity for the CCK code is not. A low cost and high performance 802.11B compatible baseband transceiver design would be proposed in this paper. Fast Walsh Transform(FWT) is the famous structure used for the CCK demodulator, such as Intersil and CCL. But FWT is not the only one solution, and I recommand another powerful one named Different Phase Transform(DPT). Many different architectures for the CCK demodulator would be illustrated in this paper, and their performance would also be compared following. High performance carrier offset estimator is an indispensable module for the shorter data duration in the new standard. A novel and powerful solution named NDAFF-CCK AFC is provided in this paper. It combined "CCK Demodulator" and "Carrier Offset Estimator(COE)" tightly. Therefore, it pay few payload, and get wonderful performance by our architecture. On the other hand, it costs less power consumption .