行動電信網路之IP封包量測

Abstract

近年來電信業者開始佈建長期演進技術（LTE）以取代3G行動網路。在LTE網路的佈建過程中，電信業者與電信設備製造商需要對使用者設備（UE）以及基地台（eNB）進行功能性與效能的測試。本論文建置了一個測試分時雙工長期演進技術（TD-LTE）與分頻雙工長期演進技術（LTE FDD）效能的實驗環境，用以量測不同電信設備製造商所製造之UE或eNB的效能。具體來說，本研究量測TD-LTE和LTE FDD傳輸IP封包、TCP封包與網路電話（VoIP）封包的延遲（latency）效能與吞吐量（throughput）效能。除此之外，我們並量測了全球互通微波存取（WiMAX）、分時同步分碼多工存取（TD-SCDMA）與寬頻分碼多工存取（W-CDMA）的效能，然後與TD-LTE與LTE FDD的效能比較。這些量測結果可以供電信設備製造商作為改善其產品效能的參考依據，也可以供電信業者作為其佈建未來網路與選擇UE的參考依據。

另一方面，我們提出了兩種量測平均意見分數（MOS）數值的方法以評估網路電話的通話品質。本論文所提出的方法在使用者裝置上安裝一個簡單的程式（透過類似app store的方式），讓使用者可以在撥打或接聽通話之前先預估通話的品質。本文所提出的兩個方法中，第一種方法使用查表的技術，將感知語音品質評估（PESQ）量測MOS值的時間從315.4秒減少到3秒，第二種基於E-model的方法可以在5.35秒內量測出準確的MOS值。此結果顯示本文所提出的兩個方法均可即時量測網路電話的通話品質。

In the recent years, Long Term Evolution (LTE) systems have been developed to replace 3G mobile networks. During the LTE network deployment, it is essential that the mobile operators and manufacturers conduct tests on user equipment (UE) and base station (eNB). This dissertation develops a LTE test environment that can be used to test the Internet Protocol (IP)-based packet performance for Time Division - Long Term Evolution (TD-LTE) and Long Term Evolution Frequency Division Duplex (LTE FDD). Specifically, we consider the latency and the throughput performance of IP, TCP, and voice over Internet protocol (VoIP) packet delivery. This multi-purpose test environment can be utilized to investigate the performance of UE and/or eNB of various manufacturers. Furthermore, we also measure the latency and throughput performance of Worldwide Interoperability for Microwave Access (WiMAX), Time Division - Synchronous Code Division Multiple Access (TD-SCDMA) and Wideband Code Division Multiple Access (W-CDMA), and compare them with the performance of TD-LTE and LTE FDD. The measurement results provide guidelines for the LTE UE and eNB vendors to improve their products, and the operators to deploy their future networks and subsidized UEs.

On the other hand, to measure VoIP quality, we proposed two MOS measurement approaches for mobile devices. In our approaches, a simple program is installed in each of the mobile devices (through an app-store like mechanism). In the PESQ MOS measurement approach, a lightweight real-time table lookup solution significantly reduces the computation time of PESQ MOS from 315.4 seconds to 3 seconds. In the E-model MOS measurement approach, MOS value can be accurately computed in 5.35 seconds. These results indicate that the proposed approaches can effectively provide the real-time VoIP quality measurement.