在LTE網路環境中紓解機器通訊的裝置觸發壅塞方法

Abstract

隨著物聯網裝置的迅速成長，業界已大膽推估在2019年時將會有250億個裝置連上網路。有鑒於此，巨量的信令訊息極可能造成核心網路，尤其是移動管理實體(Mobility Management Entity, MME)的壅塞。在第三方合作夥伴計畫(3rd Generation Partnership Project, 3GPP)所定義的規則中，當移動管理實體拒絕裝置觸發請求(triggering request)時並不會帶有延遲重試的相關資訊。假設環境中有大量的裝置觸發請求同時送出，極可能導致移動管理實體發生壅塞，進而引起觸發失敗。在此我們提出了一個嶄新的觸發排程方法，其根據裝置觸發請求帶有的可容忍延遲時間以及優先順序，有效降低移動管理實體的壅塞。另外我們也提出將相同資訊的訊息進行聚合以減少需要傳送的訊息量。模擬結果顯示相較於傳統的觸發排程方法，當採用我們的方法時將可同時處理更多的裝置觸發請求，並且有效提高裝置觸發請求的成功率。

The number of Internet of Things (IoT) devices is forecasted to reach 25 billion in 2019. Since a large number of devices may be connected to the Internet at the same time, the explosive signalings may quickly congest the core network, especially at Mobility Management Entity (MME). In the current 3rd Generation Partnership Project (3GPP) specification, when a triggering request for a device arrives at the MME, if the MME is overloaded, it will be rejected without giving any back-off information. Since IoT devices may be put into sleeping quite often, MMEs are expected to handle a great deal of such triggering signals simultaneously. Therefore, some congestion-preventing mechanism is needed to protect MMEs. In this work, we propose an efficient scheme considering triggering requests’ delay tolerance and priorities to alleviate the signaling congestion. Our approach tries to reschedule request can at proper times, thus decreasing their fail probability. Besides, we observe that such signaling messages are usually quite large and carry common information. A divide-and-aggregate mechanism is designed to reduce such common information transmission. Simulation results show that our scheme can handle more triggering requests and increasing signaling success probability significantly compared to typical schemes.