用於低功率限制下傳輸速率控制技術在無線近身網路之演算法設計

Abstract

無線近身網絡（WBAN）是一種結合了裝置於人體身上的嵌入式感測器以便於從多個病人身體上監測相關生理參數的無線網路. WBANs 增加了病患的舒適性和便利的移動性，同時也允許在必要的時候可以進行遠程醫療看護的需求。本論文提出新的速率適應性相關 MAC 通訊協定，針對 WBAN 所處的網路環境不同，採用動態的調整無線傳輸調變技術來抵抗當時的雜訊，以期能藉由適時地選擇不同的資料傳送速率方式，達到較高的資料傳送可靠度，並依此選出最有利之傳輸速率，縮短傳輸所佔用之網路時間，以提升網路產能及改善整體傳輸時的能量消耗。此外本論文採用即時偵測所得到的接收端訊號強度指示（Received-Signal-Strength-Indicator，RSSI），得知當下網路上通訊的品質，並藉著平均 RSSI值 (Average-RSSI)的計算來判斷網路中訊號品質的波動，如此將比傳統使用 RSSI 臨界值之方法，更能貼近網路品質狀況的真正表現。透過本論文所提出的方法動態地選擇速率，可獲得更理想的傳輸效能。實驗結果呈現出，我們所提出的方法考量了未來網路品質的變化，並快速地針對網路品質調整傳輸方式，可得到較好的網路效能，以及更高的傳輸可靠度，並同時大幅地降低了資料傳輸的能量消耗。

A wireless body area network (WBAN) is a wireless network that incorporates embedded sensors on the human body with the aim to monitor physiological parameters from multiple patient bodies. WBANs increases the comfort and mobility of patients while allowing remote access of data whenever necessary. The paper proposes an adaptive rate switching MAC protocol for WBAN to resist the frequent changing of channel quality and meanwhile, the protocol increases the network throughput and decreases the energy consumption. In wireless environments of WBAN, channel quality varies with time. The proposed protocol dynamically detects the current RSSI to estimate the channel quality through the previous average RSSI value calculated. According to the results generated from the proposed protocol, the proposed protocol enables a transmitter WSN to select an appropriate transmission rate dynamically to transmit in order to both increase the reliability and shorten the channel access time of the transmission. The simulation results show our proposed protocol has better performance, higher transmission reliability, higher network throughput and lower transmission energy consumption by the rate matching.