應用於無線近身網路的動態取樣相位頻率調整技術

Abstract

近年來無線近身網路的應用已經逐漸受到重視，尤其是應用於人體生醫資訊的偵測，預期可以大大降低醫療成本以及提高醫療成效。在這樣的應用中，偵測點加傳送端會被放在人體上，它的主要訴求會是越低的功率消耗，以避免時常要更換電池的麻煩。接收端可以被整合在手機或是個人數位助理等裝置，主要訴求是提升整個系統的效能，以確保生醫訊號無線傳輸的可靠度。 本篇論文將介紹一個應用於無線近身網路，結合正交多工分頻及分碼多重存取技術的基頻收發器。正交多工分頻技術具有長的信號週期有利於消除多路徑通道中的選擇性衰減，能符合高速及高傳輸品質要求。分碼多工存取技術提供無線近身網路能同時有多個傳送端傳送資料，同時也提升訊號對雜訊的免疫力。除此之外，本篇論文也將提出應用於此系統的動態取樣相位頻率調整技術搭配一個可以調整相位及頻率的時脈產生器，來避免接收端使用2倍取樣以上的類比轉數位電路，以降低接收端類比轉數位電路的功率消耗達46.45%，而同時，動態取樣相位頻率調整也能針對傳送端和接收端的時脈不協調作偵測及調整，其結果跟傳統的只單純補償資料比較，在AWGN通道的模擬環境上，在傳輸的封包錯誤率達到1 %時，會使整體的效能提高0.8dB。

In this thesis we propose a MT-CDMA baseband processor for Wireless Body Area Network application comprising the dynamic phase and frequency recovery scheme to assure the overall system power reduction and performance improvement. In recent years, health monitoring has gradually attracted many attentions. In such applications, a transmitter node will be placed on human body for long time monitoring, while the receiver can be bundled into mobile phones or PDAs. Low power demand for transmitter node and good transmission performance is required in this system. We propose a MT-CDMA system for this application, using the advantage of orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA). Besides that, a dynamic phase and frequency recovery scheme is proposed for power reduction and performance improvement. By the dynamic phase recovery, signal sampling rate is reduced from Nyquist rate (or higher) to the symbol rate, resulting in reduced ADC circuit power. By the dynamic frequency recovery, data is recovered from less-interfered data. In the MT-CDMA system, the simulations show that the system improves 0.8 dB SNR and reduce 46.45% ADC power with the DFR and DPR techniques, respectively.