窄頻物聯網是第三代合作夥伴(3GPP)計劃用於支援廣域物聯網的標準，甚至作為第五代行動通訊網路(5G)中大規模機器型通訊(mMTC)項目的基礎。在窄頻物聯網系統中，本篇論文提出一基於時間前置機制之隨機存取程序的改良型架構(enhanced timing advance based random access procedure, eTARA)，此架構完全相容於3GPP標準中的隨機程序。eTARA透過提出的改良型架構，使用裝置間與基地台距離不一的特性解決裝置間潛在的碰撞問題並降低隨機存取所花費之傳送次數，自適應決策演算法能有效抑制多重路徑的影響，並讓部分碰撞中裝置提早離開碰裝中之隨機存取程序，以提升裝置成功連網機率。此外，改良型架構透過自我放棄機制，減少裝置平均在隨機存取程序中的傳送次數，進而增加省電效率。透過模擬程式驗正改良型架構是否達成預期效益。

Narrowband Internet of Things (NB-IoT) is a new 3GPP standard aiming to support a massive number of device features long range, low complexity, low power, and low data rate. The 5th generation mobile communication (5G) massive machine type communication (mMTC) field will base on NB-IoT system. In this paper, we proposed an enhanced scheme target for solve the limitation of traditional timing advance based random access procedure (TARA), called enhanced TARA (eTARA) which is completely compatible with 3GPP standard’s random access procedures, we consider high delay spread effect between UE and eNB, proposed algorithm can automatically adjust to adapt different level of delay spread effect, eTARA also reduce the number of MSG3 transmission times in terms of reducing power consumption. Performance of eTARA procedure verified by computer simulation, comparison with TARA procedure and convention RA procedure.

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