IEEE 802.11a 無線區域網路之正交分頻多工接收機的設計與模擬

Abstract

為了要提供高速無線區域網路的需求，IEEE 802.11a標準被制定出來。它採用了OFDM的調變方式，所提供的資料傳輸速率為6Mbps~54Mbps。這篇論文將依據IEEE 802.11a標準內所規定的封包格式設計其基頻接收機架構，其中將包含封包檢測、符元時序估計、粗略及細微載波頻率偏移估計、通道估計、相位偏移估計及資料檢測等部份。每個部份將針對其運作原理及演算法做詳細的介紹，在每個部份中盡可能在性能表現及運算複雜度兩者間取一平衡點。為了驗證接收機的效能，我們針對不同的通道環境進行電腦模擬，模擬的內容包含每個部份的性能表現以及在不同條件下的BER和PER，探討出哪個部份對系統性能表現的影響最為嚴重，以便於日後要提升接收機性能時的依據。我們最後提出結論與未來的研究方向。

The IEEE 802.11a standard was defined in order to support the demand of high data rate WLANs. It adopts OFDM modulation and provides data rates from 6Mbps to 54Mbps. In this thesis, we propose an IEEE 802.11a baseband receiver architecture according to its specified packet format. The receiver includes several functional parts: packet detection, symbol timing estimation, coarse and fine carrier frequency offset estimation, channel estimation, phase offset estimation and data detection. We describe the operation principles and the algorithms of each part in details, and we try to make a good tradeoff between system performance and computational complexity. In order to verify the performance of the receiver, computer simulations are conducted under different channel conditions. Our simulation results include the performance of each functional part and the BER and PER of the whole system. From the simulation results, we can determine which parts are more critical to the whole system performance than others. Finally, we draw a conclusion and comment on possible future research directions.