應用於正交分頻多工技術為基礎之無石英無線近身網路同步器

Abstract

在本篇論文裡，介紹一個正交分頻多工系統的同步方法，應用於無石英震盪器之無線近身網路，來增加整個系統收發端的頻率誤差容忍度。 無線近身網路為主的健康照護的系統越來越受人們的重視，尤其是針對人體生醫訊號的偵測，可降低醫療成本以及提高醫療成效。應用情境如配戴在身上的無線感測器對人體訊號做長時間的偵測，並以無線的方式將資料傳送給整合在手機或個人數位助理的接收端。基於這樣的一個應用，極低的功率消耗跟高度整合的面積會是系統不可或缺的需求，因此我們使用了互補式金屬氧化層半導體震盪器取代傳統產生系統時脈的石英震盪器，以降低系統功率消耗以及提升整合度。 無石英震盪器現階段技術尚未成熟，使用此系統會造成收發段頻率誤差大的問題，造成整個系統收發資料損失。於是本篇論文提出了一種套用於正交分頻多工的基頻同步演算法配合一個可以調整的數位控制震盪器已達到減少收發端頻率誤差的效果。 將晶體振盪器整合進單一晶片中，可以降低系統的製造成本、面積及功率消耗。在本篇論文我們對整個正交分頻多工無線近身網路系統的行為做一個詳盡的闡述，並分析頻率校準的基頻演算法，最後建立了一個正交分頻多工的基頻原型來驗證這樣的行為。這個方法套用在此論文之應用系統可使整個系統的頻率誤差容忍度拓展為140倍，進而達到小面積，低功率，高整合度的基頻系統晶片設計。

In this thesis, we propose a synchronization method for crystal-less OFDM-based wireless body area network (WBAN) applications to enlarge the frequency error tolerance between the transmitter and receiver. WBAN systems for ubiquitous health monitoring are gradually attracting many attentions. This can reduce the medical cost and improve medical treatment outcomes. The wireless sensor node (WSN) nodes are placed on the human body allowing long-term health monitoring. Those gathered signals from a multiple of WSNs are wirelessly transmitted to a remote central processing node (CPN), such as mobile phone or PDA. Based on these applications, low power and highly integration properties are indispensable. To meet these needs, the CMOS oscillator is applied instead of the conventional quartz crystal oscillator. However, the crystal-less technology does not come to maturity. It causes large frequency error in the system using the crystal-less oscillator. We propose a synchronization method for OFDM-based WBAN systems. Applying the crystal-less oscillator in the system, the area and power can be reduced a lot. In this thesis, a complete WBAN system and the novel synchronization algorithm are described. An OFDM emulation system is also established. In our application system, the overall frequency error tolerance is expanded to 140x, enabling the tiny area and highly integration SOC design.