基於軟體無線電之寬頻無線接取系統設計

Abstract

寬頻無線網路即將給人們的生活帶來突破性的變化，不論在何時何地都能以高傳輸速率得到想獲取的資訊。WiMAX (Worldwide Interoperability for Microwave Access; 全球互通的微波存取)，目前已準備好成為新一代的寬頻無線接取技術並可提供固定式及移動式的網路服務。新興的IEEE 802.16-2005規格為了在不同的無線傳輸服務達到最佳化，整合了三種空中傳輸介面：單載波模式(Single Carrier, SC)、正交分頻多工模式(Orthogonal Frequency Division Multiplexing, OFDM)及正交分頻多重接取模式(Orthogonal Frequency Division Multiple Access, OFDMA)。在本論文中，吾人將探討SC-OFDM-OFDMA三模收發機之共同設計；藉由軟體定義無線電(Software Defined Radio, SDR)概念的引入，吾人設計之收發機架構可在單一平台上有效支援IEEE 802.16-2005所定義的三種空中傳輸介面。吾人將探討此共同設計所需之通道估測、時序同步及載波頻率估測等方法；具體而言，吾人將提出共同設計之時序及載波頻率飄移估測法。為了進一步提高系統傳輸的距離及可靠性，吾人在此架構中利用IEEE 802.16-2005所定義的多根天線傳輸技術，如時空編碼(Space-Time Coding, STC)及適應性天線系統(Adaptive Antenna System, AAS)等。最後，吾人將藉由電腦模擬驗證所提出之共同設計之SC-OFDM-OFDMA收發機架構，在無線通訊環境中具有可靠的傳輸效能，並展示出多根天線傳輸技術可帶來效能的改善。

Broadband wireless will revolutionize people's lives by enabling a high-speed connection directly to the information they need, whenever and wherever they need it. WiMAX (Worldwide Interoperability for Microwave Access) is poised to become a key technical underpinning of fixed, portable and mobile data networks. It’s the development of the emerging IEEE 802.16 standard that integrates Single Carrier (SC), Orthogonal Frequency Division Multiplexing (OFDM) and Orthogonal Frequency Division Multiple Access (OFDMA) for the optimization of different wireless data services. In this thesis, we investigate the joint design of SC-OFDM-OFDMA transceivers on a single platform via the concept of Software Defined Radio (SDR) to support various air-interface standards specified by IEEE 802.16-2005. In this way, the system possesses as many common components as possible for these three modes, and the transmitter and receiver can be switched among the three modes via SDR operation. Synchronization schemes for the SDR system are also investigated in this thesis. In particular, we propose a joint design of timing and frequency synchronization algorithm with lower computational complexity. In order to increase the range and reliability of the system, the use of multiple-antenna techniques such as Space-Time Coding (STC) and Adaptive Antenna Systems (AAS) in IEEE 802.16-2005 is also considered and verified to exhibit improved performance. Finally, we evaluate the performance of the joint design of SC-OFDM-OFDMA SDR system and confirm that it works reliably under the three modes.