802.11n & 802.16e 雙模多輸入多輸出正交分頻多工基頻接收機之設計與實作

Abstract

由於現代人對於網路的依賴，漫遊變得格外重要。因此無線雙模將可以擴展網路所能包含的面積。無線雙模支援了802.16e以及802.11n，這代表著使用者將可以在室內及室外不斷線的持續上網。 本篇論文的重點就是提出一個雙模的2x2 MIMO-OFDM / OFDMA基頻實體層接收機，此雙模接收機可操作在靜態及動態通道環境。此接收機是依據 EWC HT PHY V1.27 以及 IEEE 802.16e-2005 的功能要求，提出了實體層的OFDM / OFDMA參數以及速度參數。傳送機、通道模型是以軟體形式撰寫，而接收機是以軟體來模擬硬體，接收機的部份則更進一步的用定點數來實現。接收機的主要架構分為同步、反調變、以及等化。其中同步還包括基台搜尋、時間與頻率同步電路、載波頻率飄移與取樣時脈飄移的偵側與補償。反調變的部份包括了殘餘分數載波頻率偏移以及殘餘取樣時間偏移的聯合估計並追蹤。而等化的部份也包括了通道估計。本論文將第一及第二部份充分的做到硬體上的共用，而第三部分則包含了低硬體成本的載波間干擾消除等化器以及可共用的MIMO等化器 2x2 STBC 和 2x2 VBLAST。 藉由相關性衰減的MIMO通道以及各式的通道模型，加上各種不完美效應，像是多重路徑瑞雷衰減、動態環境下的都普勒效應、載波頻率與取樣時脈飄移等效應，而且能成功將資料還原。

The increasing reliance on the Internet in everyday life has led to more demand for roaming Internet services. The proposed dual mode wireless receiver fills this gap by increasing the coverage of the service area. By implementing both 802.16e and 802.11n, Internet access is made available in indoor and outdoor environments. The purpose of this thesis is to implement a dual mode 2x2 MIMO OFDM & OFDMA with shared hardware resources. This dual mode receiver should function well in both static channels and mobile channels. It follows the specification requirement of EWC HT PHY V1.27 and IEEE 802.16e-2005, and proposes a PHY baseband simulation model to meet the specifications. The transmitter and channel models are modeled in software. The receiver uses software to model the hardware, and a fixed-point design is implemented as well. The receiver is divided into Synchronization, Tracking, and Equalization. Synchronization includes cell search, symbol boundary detection, fractional and integer CFO estimation and compensation. Tracking performs FFT, Joint Weighted Least Square Estimation, and residual CFO and SCO estimation and compensation. Equalization includes channel estimation and MIMO equalization. Effort was made to reuse hardware between Synchronization and Tracking. Additionally, Equalization supports both dynamic and static channel estimation. 2x2 MIMO STBC and VBLAST are supported as well. A low cost ICI cancellation hardware is also proposed. By adopting various channel models, including several nonlinear channel effects such as multipath Rayleigh fading, dynamic channel Doppler effect, carrier frequency offset, and sampling clock offset, the dual mode receiver has been shown to successfully recover the transmitted signal even in non-optimal environments.