A WLAN Test System Using Test Equipment With
EDA Software
by Dingqing Lu and Jinbiao Xu
Agilent EEsof EDA
Test measurements such as EVM and ORFS for transmission tests as well as
Minimum Input Level Sensitivity and Adjacent Channel Rejection for receiving
tests are required by WLAN (Wireless Local Area Network) standards. For
such complex tests it is hard to find a system on the market to meet the
requirements. A pure hardware test solution consisting of connecting a number
of test instruments such as signal generators, channel emulators, interference
generators, signal analyzers, and receiver testers is very expensive and
difficult to be configured to meet the standard. Although some virtual analyzers
in the current market can extend functionality for some basic test equipment
this is not enough to meet the requirements for this type of complex testing.
This article describes a test system configured from basic hardware test
equipment: A signal generator and vector signal analyzer, connected with
EDA software for testing WLAN systems based on the IEEE 802.11a/g standard.
Results show that the connected hardware/software system works very well.
Introduction
Demand for WLAN systems is growing very fast within the worldwide wireless communications industry. New WLAN systems based on the IEEE 802.11a/g standards deliver higher data rates, better spectral efficiency, improved performance under multi-path fading conditions, and less interference in low-mobility wireless conditions than earlier systems. WLAN systems are widely used for wireless network connection.
To support high-rate data in the systems multi-carrier modulation, orthogonal frequency division multiplex (OFDM) is used. The basics of OFDM [1] is to split a high data rate stream into a number of lower rate streams that are transmitted, simultaneously, over several subcarriers. With lower data rates in the parallel subcarriers there is increased symbol duration decreasing the relative amount of dispersion in time (delay spread) caused by multi-path propagation. Inter-symbol interference (ISI) can be reduced significantly because an adequate guard interval can be inserted between successive OFDM symbols.
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