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Towards the quality of service for VoIP traffic in IEEE 802.11 wireless networks.

機譯：邁向IEEE 802.11無線網絡中VoIP流量的服務質量。

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摘要

The usage of voice over IP (VoIP) traffic in IEEE 802.11 wireless networks is expected to increase in the near future due to widely deployed 802.11 wireless networks and VoIP services on fixed lines. However, the quality of service (QoS) of VoIP traffic in wireless networks is still unsatisfactory. In this thesis, I identify several sources for the QoS problems of VoIP traffic in IEEE 802.11 wireless networks and propose solutions for these problems.;The QoS problems discussed can be divided into three categories, namely, user mobility, VoIP capacity, and call admission control. User mobility causes network disruptions during handoffs. In order to reduce the handoff time between Access Points (APs), I propose a new handoff algorithm, Selective Scanning and Caching, which finds available APs by scanning a minimum number of channels and furthermore allows clients to perform handoffs without scanning, by caching AP information. I also describe a new architecture for the client and server side for seamless IP layer handoffs, which are caused when mobile clients change the subnet due to layer 2 handoffs.;I also present two methods to improve VoIP capacity for 802.11 networks, Adaptive Priority Control (APC) and Dynamic Point Coordination Function (DPCF). APC is a new packet scheduling algorithm at the AP and improves the capacity by balancing the uplink and downlink delay of VoIP traffic, and DPCF uses a polling based protocol and minimizes the bandwidth wasted from unnecessary polling, using a dynamic polling list. Additionally, I estimated the capacity for VoIP traffic in IEEE 802.11 wireless networks via theoretical analysis, simulations, and experiments in a wireless test-bed and show how to avoid mistakes in the measurements and comparisons.;Finally, to protect the QoS for existing VoIP calls while maximizing the channel utilization, I propose a novel admission control algorithm called QP-CAT (Queue size Prediction using Computation of Additional Transmission), which accurately predicts the impact of new voice calls by virtually transmitting virtual new VoIP traffic.
機譯：由于廣泛部署的802.11無線網絡和固定線路上的VoIP服務，預計在不久的將來IEEE 802.11無線網絡中IP語音（VoIP）流量的使用將增加。但是，無線網絡中VoIP流量的服務質量（QoS）仍然不令人滿意。本文主要針對IEEE 802.11無線網絡中VoIP流量的QoS問題找出幾種來源，并提出解決方案。討論的QoS問題可分為用戶移動性，VoIP容量和呼叫接納三類?？刂啤Ｓ脩粢苿有詴谇袚Q過程中導致網絡中斷。為了減少接入點（AP）之間的切換時間，我提出了一種新的切換算法，即選擇性掃描和緩存，該算法通過掃描最少數量的信道來找到可用的AP，并且還允許客戶端通過緩存AP來執(zhí)行不掃描的切換信息。我還描述了用于無縫IP層切換的，用于客戶端和服務器端的新體系結構，這是當移動客戶端由于第2層切換而改變子網時引起的。我還提出了兩種方法來提高802.11網絡的VoIP容量：自適應優(yōu)先級控制（APC）和動態(tài)點協調功能（DPCF）。 APC是一種新的AP數據包調度算法，它通過平衡VoIP流量的上下行延遲來提高容量，而DPCF使用基于輪詢的協議，并使用動態(tài)輪詢列表將不必要的輪詢所浪費的帶寬最小化。此外，我通過在無線測試臺中進行理論分析，仿真和實驗，估計了IEEE 802.11無線網絡中VoIP流量的容量，并展示了如何避免測量和比較中的錯誤。最后，保護現有VoIP的QoS在最大程度地利用信道的同時，我提出了一種新穎的準入控制算法QP-CAT（使用附加傳輸計算的隊列大小預測），該算法通過虛擬傳輸虛擬的新VoIP流量來準確預測新語音呼叫的影響。

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  • 作者

    Shin, Sangho.;

  • 作者單位

    Columbia University.;

  • 授予單位 Columbia University.;
  • 學科 Computer Science.
  • 學位 Ph.D.
  • 年度 2008
  • 頁碼 213 p.
  • 總頁數 213
  • 原文格式 PDF
  • 正文語種 eng
  • 中圖分類 自動化技術、計算機技術;
  • 關鍵詞

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