用於行動照護應用之 低能量OFDM調變基頻收發器設計

Abstract

隨著已開發國家醫療品質的提升和邁向人口高齡化的結構，利用可攜式電子儀器提供全天候的醫療照護，無論是對於患者或者一般民眾的健康都提供更進一步保障。醫院的服務不再侷限於會診室，將拓展到任何空間。為滿足該使用情境，因而發展出無線近身區域網路 (Wireless Body Area Network, WBAN)系統，該系統應用目前也正被IEEE 802.15.6 (TG6) 組織所制訂成一通用標準規範。 為了提供長時間的生理訊號監測, 無線近身區域網路需要為一個超低功耗設計並且維持可靠的訊號傳輸. 許多現存的標準 規範，如: ZigBee、Bluetooth 和一些低階調變的系統，雖然都曾是無線近身區域網路應用的候選系統，然而在系統的功耗和可靠度仍無法滿足上述需求。 藉由分析無線近身區域網路運作特性，提出較高的傳輸位元率以及較低的功耗傳輸端設計。本篇論文中介紹一個以用於行動照護的OFDM調變機頻收發器。系統提供了Mbps數量級的傳輸位元率以及高可靠性的訊號傳輸品質。設計的系統也考慮的一些非理想效應，例如：在無線近身區域網路中的多路徑衰減通道效應以及在正交分頻多工系統中常見的載波頻率飄移以及取樣頻率飄移。此外，我們設計一個簡單的通道編碼器去降低在傳送端的功率放大器能量消耗，低功耗的技術也在實現在晶片設計。 提出的基頻收發器採用90奈米標準CMOS製成晶片實現。在0.5V 的電源供應之下，收發器的功率消耗為450.22μW。系統提供了5.82Mbps的傳輸位元率以及傳輸的活動週期為0.1768%，此外系統每傳輸一個位元所需的功率消耗為 0.639 nJ。最後我們建立一個心電訊號傳輸模組來驗證我們所提出的醫療照護應用的基頻收發器。

With the developed countries and improving the quality of health care towards an aging population structure, using portable devices for healthcare all day, no matter for the patients or the general public to provide further protection. This extends medical services from the closed in-hospital system to any open roaming space. In order to meet the scenarios, the Wireless Body Area Network system is developed. The WBAN system will be developed into a common standard rules by IEEE 802.15.6(TG6). In order to achieve long duration monitoring, the WBAN system is required to provide a reliable transmission with ultra-low power consumption. Those well-defined WBAN systems, such as Bluetooth and ZigBee, are designed for widespread applications. However, these candidate systems have difficulties to meet consumer electronic devices and healthcare systems at the same time due to the power cost. Based on the analysis of the WBAN operation behavior, higher data rate and low power implementation techniques are proposed to reduce the transmission energy. This work proposes an OFDM based baseband transceiver design, which provides Mbps-level data rate and reliable transmission, for WBAN application. We also consider the non-ideal effect in system, such as multi path effect in WBAN channel, carrier frequency offset and sampling clock offset in OFDM based transceiver. The channel coding is designed to reduce the power consumption in the transmitter power amplify and the low power technique is proposed in chip implementation. The chip is implemented in a 90nm CMOS technology, and this baseband transceiver dissipates 450.22μW with supply voltage 0.5 V. The proposed system provides maximum 5.82 Mbps data rate, resulting in active duty cycle of 0.1768% and the transmission energy of 0.639 nJ / bit. Finally, an ECG transmission platform is established with the proposed design for real-time health-care system evaluation