Congestion Control for Machine Type Communications in LTE

[[abstract]]隨著科技技術的發展，越來越多智慧型設備可以偵測各類環境狀況，並且在無人為介入下自動回報後端伺服器系統，這類似無線感測網路應用已有多年發展。3GPP在制定新一代無線行動通訊LTE過程中，SA工作群組也同時發展機器對機器(Machine-to-Machine, M2M)通訊，或稱為機器類型通訊(Machine Type Communication, MTC) 之相關技術。SA工作群組設計的MTC應用亦希望不透過人為操作下，MTC終端設備可以直接傳輸給後端 MTC伺服器。隨著應用越來越廣，未來MTC裝置及通訊的數量會以驚人的速度成長。然而MTC終端設備大量增加時，對於網路傳輸需求相對也會增加，當然就易造成LTE網路環境負擔，尤其是MTC裝置嘗試連結上LTE網路時，因為RACH可使用之 Preamble數量十分有限，壅塞現象勢必無法避免。本論文嘗試利用分群方式將MTC裝置劃分不同群組以形成階層式架構，利用ACB/EAB分散機制及群組Paging等方式來降低發生壅塞的機會。本論文並計畫設計適用於MTC環境的Device-to-Device(D2D) 通訊進一步減少LTE網路的負荷。[[abstract]]With the development of IT technologies, more and more intelligent devices can detect many kinds of environmental conditions, and send collected data or alarm back to server system automatically. Such applications, similar to wireless sensor networks, are developed for recent years. With the development of next-generation LTE wireless mobile network, SA working group also develop a related technologies, namely Machine Type Communication (MTC), in 3GPP. The MTC applications developed by 3GPP SA working group are also operated without interactive with human and can transmit data directly to servers located in LTE core network. However, the MTC devices may massively increase due to more and more fancy applications used. This may result in LTE core network over load as the transmission demand increased. Moreover, RACH congestion becomes more and more serious due to limited preamble slots in LTE system. This thesis attempts to use a hierarchical architecture for grouping MTC devices based on their futures. The ACB or EAB combined with group paging mechanisms are used to reduce the probability of congestion happen. Furthermore, this thesis also develops a Device-to-Device, D2D, communication approach to further reduce the LTE system load.[[note]]碩