Worcester Polytechnic Institute Electronic Theses and Dissertations Collection

Title page for ETD etd-082206-234807


Document Typethesis
Author NameMetreaud, Leon T
URNetd-082206-234807
TitleAn RF-Isolated Real-Time Multipath Testbed for Performance Analysis of WLANs
DegreeMS
DepartmentElectrical & Computer Engineering
Advisors
  • Prof. Kaveh Pahlavan, Advisor
  • Prof. Fred Looft, Department Head
  • Prof. Allen Levesque, Committee Member
  • Prof. Wenjing Lou, Committee Member
  • Keywords
  • WLAN performance
  • throughput modeling
  • RF-isolated testbed
  • channel emulation
  • Date of Presentation/Defense2006-08-17
    Availability unrestricted

    Abstract

    Real-time performance evaluation of wireless local area networks (WLANs) is an extremely

    challenging topic. The major drawback of real-time performance analysis in actual network

    installations is a lack of repeatability due to uncontrollable interference and propagation complexities. These are caused by unpredictable variations in the interference scenarios and statistical behavior of the wireless propagation channel. This underscores the need for a Radio Frequency (RF) test platform that provides isolation from interfering sources while simulating a real-time wireless channel, thereby

    creating a realistic and controllable radio propagation test environment. Such an RF-isolated testbed is necessary to enable an empirical yet repeatable evaluation of the effects of the wireless channel on WLAN performance.

    In this thesis, a testbed is developed that enables real-time laboratory performance evaluation of WLANs. This testbed utilizes an RF-isolated test system, Azimuth™ Systems 801W, for isolation from external interfering sources such as cordless phones and microwave ovens and a real-time multipath channel simulator, Elektrobit PROPSim™ C8, for wireless channel emulation. A software protocol analyzer, WildPackets Airopeek NX, is used to capture data packets in the testbed from which statistical data characterizing performance such as data rate and Received Signal Strength (RSS) are collected. The relationship between the wireless channel and WLAN performance, under controlled propagation and interference conditions, is analyzed using this RF-isolated multipath testbed.

    Average throughput and instantaneous throughput variation of IEEE 802.11b and 802.11g WLANs

    operating in four different channels – a constant channel and IEEE 802.11 Task Group n (TGn)

    Channel Models A, B, and C – are examined. Practical models describing the average throughput as a function of the average received power and throughput variation as a function of the average throughput under different propagation conditions are presented. Comprehensive throughput models that incorporate throughput variation are proposed for the four channels using Weibull and Gaussian

    probability distributions. These models provide a means for realistic simulation of throughput for a

    specific channel at an average received power. Also proposed is a metric to describe the normalized throughput capacity of WLANs for comparative performance evaluation.

    Files
  • lmetreaud.pdf

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